Llansadwrn (Anglesey) Weather:
Monthly and Annual
Summary for 2008
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Llansadwrn (Anglesey) Weather:
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Note: Values in (.) refer to the 10-y 1998-2007 average; [.] refer to the 30-y 1971-2000 climatological average while {.} refer to the station LTA (long-term average) from 1979. All data are subject to verification and amendment. Javascript must be enabled to see the pop-up graphics.
The month began with near normal temperatures and air frosts, the rest was very wet with above average temperatures
Total rainfall was 189.9 mm (168%) of the 1998-2007 average and [194%] of the 1971-2000 average. It was the wettest January since 1999 that had 193.4 mm and ranking 3rd on the Llansadwrn record kept since before 1928. The wettest January was 1948 mm with 230.9 mm recorded at Treffos. Rainfall duration was 127.0 h. The 48.8 mm recorded on the 9th was the 3rd largest fall in a day I have measured at this station set up in 1979. Rain days with 0.2 mm, or more, numbered 23 (+3.0) and wet days with 1 mm, or more were 20 (+4.5). Days with 5 mm, or more were 12 (+4.7), but there were 6 completely dry days these (-1.0) of the decadal average. Soil remained close to its saturated water percentage 70% most of the month with standing water on 6 mornings.
The temperature record continues to show the effect of climate change. The monthly mean was 6.5C (+0.7) and a large [+1.6] of the 30-y climatological average. The mean maximum was 8.9C (+0.7) and [+1.5], the highest maximum was 10.9C (-1.1) and one of 12 days that had 10C, or more, in the month. The lowest maximum was 2.5C on the 3rd, this was a cold day (-1.5) of average, but the maximum was just 1.6C on the day, the 2.5C was recorded at 09 GMT the following day and by convention was credited to the 3rd. The mean minimum temperature was 4.1C (+0.7) and [+1.7]. The highest minimum was 9.4C (+0.4) on the 21st while the lowest was -0.5C (+1.1) on the 4th. The only other day to see an air frost was the previous day (3rd) with -0.3C. In all there were just 7.5h of air frost. Ground frosts numbering 12 were closer to normal (+0.3) with the lowest -3.7C (+2.1) on the 12th. The soil temperature at 30 cm was 6.4C and (+1.1) of average. There were 22 days on which the temperature was >= 5.6C or 42F, this is regarded as the minimum temperature for plant root growth. The soil surface was frozen on just 2 days, the 3rd and 4th.
The was small hail on 9 days, slight snow on 1 day, but no lying snow at 0900 GMT. A covering of snow pellets and snow lay for about 20 minutes from 1620 GMT on the 31st. No thunder was heard.
The period 11 - 19th had almost clear skies and night frosts
The month was outstanding for its sunshine with the Met Office at RAF Valley recording 120.8 h of sunshine on the Kipp & Zonen instrument. Since the Campbell Stokes 'glass sphere and card' instrument was consigned to the museum it has been difficult to compare the present reading with previous. Using the correction (see Notes 1 below) it was (153%) of average and sunniest since 1986 and ranked 5th sunniest on the Anglesey record since 1930. The sunniest day was on the 18th with 9.1 h, but the spell 11 - 19th had more than 8 h each day. It was not all sunshine as there were 7 sunless days spread over the beginning and end of the month.
Temperatures were above average, the mean in Llansadwrn was 6.1C (+0.7) and [+1.3] of the decadal and 30-y averages. The highest mean was on the 9th with 10.1C and the lowest 2.6C on the 17th. It was the maxima that excelled with the mean 10.4C highest since 1998 (10.5C) 2nd highest since before 1979 being the only 2-years into double figures. The highest maximum of 16.8C on the 11th (+4.4), in Föhn-like conditions with a relative humidity down to 34%, was the highest recorded at this station so early in the year (previously 16.5C on 10th January 1998), and the 2nd highest in February to the 17.2C recorded on the 28th in 1985. On the same day Trawsgoed in Ceredigion (it seems now to have a g in it and may a different location to the Trawscoed previously reported) had 16.1C, but not to be outdone on the 12th had a summer-like 18.2C while here it was only 14.1C. There was 16 days on which the temperature reached 10C, or more. The mean earth temperature at 30 cm was 5.8C (-0.2)
There were some frosty days too with air frost recorded on 5 days (+1.9), most since 2004. The mean minimum was 2.9C (-0.3) and [+0.8] indicating lower than in recent years, but higher than the climatological average 1971-2000. Lowest was -1.3C on the 18th which was on the average, and highest 8.0C (-0.3) on the 8th. There were 27.6 h of frost duration, most 10.2 h on the 17th. There were 19 (-0.2) ground frosts, close to the average of the last 10-years.
Rainfall of 68.9 mm , drier than the past 10-years (74%) and closer to the 30-year average [92%]. The wettest day, on the dull extra leap-year day 29th, had 16.3 mm. There were 10 (+3.8) dry days and 14 (-4.0) rain days. Wet days were 11 (-2.5) while days with 5 mm, or more, were 5 (-1.2).
There was snow sleet or snow and the 3 days with hail was (-2.9) of average. There was no thunder, but there were 3 days with gales.
The mean air temperature of 6.5C, lowest since 2006 ranking 10th since before 1979, was 0.7C below the average of the past 10-y but only 0.2C below the 1971-2000 average. The month was more like an average March experienced before the warming trend of the past 30 years. Locals were complaining of how cold it was, they were either too young or had short memories of how it used to be! The mean maximum was 9.8C (-0.7) and [-0.4], the highest maximum on the 31st was 14.6C and was (-1.9) of average. The lowest 6.8C occurred on 2 days the 22 and 23rd and were (+1.0) of the decadal average. The mean minimum 3.3C was again (-0.7), but spot on the 30-y average [0.0]. The highest minimum of 6.3C (-2.3) on the 2nd was lowest since 1984 that had 6.1C and the lowest -0.1C was highest on record since 1979 and the only day with air frost (-1.7). There were 11 (-0.3) ground frosts, interspersed through the month, with the lowest -3.8C (+2.6) on the 5th when 0.17 mm of dew and frost deposits were recorded. The mean temperature of the soil at 30 cm was 6.9C (-0.4), all above the 5.6C or 42F regarded as necessary for plant growth. Lawnmowers were out during the month, in the past they were not out until April!
Rainfall was 96.1 mm (131%) and [113%] of average, highest since 2006 and ranking 18th wettest in Llansadwrn since 1928. The largest fall was on the 15th with 20.6 mm. There were 4 (-5.6) completely dry days and 22 (+5.7) rain days. Wet days numbered 18 (+6.7) while those with 5 mm, or more 6 (+1.5). Evaporation measured by the Piche evaporimeter was 41.7 ml (or mm), evapotranspiration by lysimeter, increasing this month, with 19.6 mm. There were some windy days (21,22) with low relative humidity when Piche evaporation was 4.9 and 2.4 ml respectively. Despite increasing evaporation soil water remained close to saturation levels (water content 70% dry mass here) and several 'wet fields' near the weather station have had standing water on them most of the month. The wetness has made cultivation difficult although 2 or 3 of the drier fields have been ploughed and sown with barley. Local soils are of variable structure and most shallow of rather poor agricultural quality many being on glacial drift. The wettest areas should be mire (wetland) vegetation and there are a few examples of these that have survived, but many have been improved over the years and are difficult to maintain when it is wet. It is these fields that usually attract flocks of curlews and lapwings.
Sleet (larger amounts) , or snow (small amounts) were seen on 6 days (+3.8), but there was none lying. Small hail fell on 12 days (+7.6) and included 6 days with snow pellets and 6 days with ice pellets.
It was a windy month with 5 gales recorded at RAF Valley (9,10,11,12 and 28). The mean wind speed for the month was 18.1 mph with the highest 33.2 mph recorded on the 12th which also had the highest gust of 70 mph.
Sunshine duration at RAF Valley totalled 127.8h with 5 sunless days and just 0.1h and 0.6h recorded 2 others. Sunniest days were on the 17th with 10.7h and 27th with 10.2h. The 17th was the brightest day in Llansadwrn with global solar radiation reaching 17.52 MJ m-2. The dullest day was on the 20th with 3.07 MJ m-2. The mean daily solar radiation was 9.35 MJ m-2. Estimated sunshine duration was 125.2 h with 8 sunless days.
The mean temperature 8.3C was -0.9 of the 10-year, but just -0.3C of the 30-year average. So a little cooler than we have been experiencing of late, but much nearer Aprils of past years. The mean maximum was 11.9C [(-0.9)] the same on both averages. The highest maximum 19.2C (+0.6) was on the 22nd and the 23rd with 16.0C were the only days to have more than 15C and there were 8 sub-10C days, scattered through the month, with the lowest 5.7C on the 6th. The mean minimum was 4.7C (-0.8) and [+0.3] clearly showing the contrast between the last decade and the climatological 1971-2000 average. The lowest minimum was -0.1C on the 6th the only air frost of the month, was for such a short time that the chart recorder used for determining hours of frost did not record it. The bi-metallic strip temperature recorder responds slower than the standard mercury thermometer. There were 11 days of ground frosts (+4.9) of average with the lowest -4.4C (-1.3) on the 8th. Soil temperature at 30 cm averaged 9.5C (-0.7), lowest 8.2C on the 7, 9 and 10th and highest 11.2C on the 25, 27 and 30th. All 6 soil thermometers (5 cm to 100 cm) registered more than 10C for the first time this year on the 23rd.
Rainfall was 86.2 mm spread throughout the month, largest falls 11.0 mm on the 12th and 10.5 mm on the 29th. There were 5 (-4.3) dry days and 21 (+3.8) rain days. Wet days numbered 18 (+4.1) while there were 7 (+1.4) with more than 5 mm. Evaporation by the Piche was 35.1 ml (or mm) and by the lysimeter 37.5 mm. There was a potential water balance of 48.7 mm, the soil remaining close to the saturated water percentage of the local soil (70%) through the month. Moderate amounts of rainfall left standing on 9, 15, 27 and 30th and it was pretty wet underfoot at other times putting work on the garden vegetable plot on hold.
At RAF Valley sunshine duration was 168.2 h (105%) and [107%] of average. Sunniest day was on the 16th with 11.3h and there were 3 sunless days. Here sunshine based on the solarimeter reading was also 168 h with 7 sunless days. The mean global solar radiation was 13.92 MJ m-2. Highest was 23.20 MJ m-2 on the 16th and lowest 5.36 MJ m-2 on the 21st.
The mean temperature 13.6C was (+1.7) and [+2.1] when based on the 10-y and 30-y averages respectively and was the highest recorded at this station since before 1979 beating 1990 with 13.4C into 2nd place. The highest mean of the month 20.1C was on the 8th and the lowest 9.4C on the 19th with the only other sub-10C 9.5C on the 1st. The mean maximum temperature was 17.4C (+1.8) and [+1.4] ranking 6th highest here with 1990 holding on to the record with a mean of 19.2C. The highest maxima were 25.1C (+1.7) on the 8th and 25.0C on the 7th, again not as high as the 27.6C recorded in 1990 or the 26.4C in 1989. In 1990 there were 4 days with 25C, or more. At Valley the mean maximum temperature was 17.5C, the highest on record, with 24.9C on the 8th. In Llansadwrn there were 6 days on which the temperature reached 20C, or more, equal highest since 2001 ranking 8th. The mean minimum here was 9.7C (+1.5) and [+2.7], and at Valley 10.3C, both highest on record. The lowest minimum was 4.8C (+1.1) on the 1st of the month while at Valley it was 5.8C on the 19th (5.1C here). The highest minimum was 15.4C on the 4th, second highest in May, and highest this early in the year since records began in 1979 (17.0C on 17 May 2002) while at Valley it was 14.0C. The mean grass minimum was 7.5C (+1.3) while it was 7.4C at Valley. The lowest grass minimum was 1.7C (+1.4) on the first and 1.9C on the 19th when Valley recorded their lowest of 1.3C. Soil temperatures at 30 cm depth increased through the month, beginning 10.4C and ending 15.5C. The mean soil temperature was 14.4C (+0.8)
Rainfall was 33.4 mm (48%) and [58%], the lowest total since 1998 (25.3 mm) ranking 14th driest since before 1928. The wettest day was on the 4th with 8.3 mm. There were 17 (+5.6) dry days, 11 (-5.1) rain days and 9 (-2.9) wet days.
Sunshine duration at RAF Valley totalled 232.3 h while the estimated duration in Llansadwrn was 221 h. At valley the sunniest day was on the 31st with 15.5 h and there were 2 sunless days (26,28) while the 9th had 0.1h and the 17th 0.4h. Global solar radiation at Llansadwrn was a mean of 18.74 MJ m-2 with the highest 27.09 MJ m-2 on the 18th and the lowest 6.38 MJ m-2 on the 9th.
Rainfall for the first 16 days was only 7.5 mm (11% of average) and the moisture content of surface soil (0-5 cm) fell to 30.4% dry mass, the permanent wilting percentage for the local soil is 15.2% and no wilting was seen although plants in the garden required irrigation.
 "Potential monthly evaporation and soil water balance up to 16 June 2008.")
The second half made up for the lack of water in the first with heavy falls on the 17th (14.3 mm), 17th (22.6 mm), 21st (18.6 mm) and 26th (40.7 mm). The latter was the largest fall in a day at this station since 1979, and in Llansadwrn since 1929 when records began. The month ended with 123.5 mm (168%) and [186%] of average, just exceeding the 122.1 mm of 2007 and was wettest since 1998 and ranking 9th  "Top 10 previous wettest years in Llansadwrn with June subtotals."){kind=small}
. There were 13 (+2.6) dry days and 16 (+0.3) rain days (0.2 mm, or more). There were 12 (+1.1) wet days (1 mm, or more) and 6 days had 5 (+0.9) mm, or more . Potential evapotranspiration (PE) to the 16th (last day of dry spell) measured by lysimeter was 49.3 mm resulting in a negative potential water balance (PWB) of 41.8 mm. The month ended with a PE of 69.3 mm and a positive PWB of 54.2 mm.
The mean temperature of 13.5C, equal lowest since 2002, was 0.1C lower than May and was 1.0C lower than average of the past 10 years. It was much closer to the 1971-2000 average just 0.1C lower. The mean maximum 17.2C, 0.2C lower than May, was [(-0.5)] compared with both averages. The highest maximum 22.8C (-2.4) was on the 9th and with the 22.0C on the 8th were the only two reaching 20C, or more. The mean minimum 9.7C was (-1.6) and [+0.2] with the highest minimum 13.0C (-2.0) on the 25th and lowest 6.0C (+0.1) on the 13th. The mean grass minimum 7.7C was also down on the average (-1.2), the lowest 3.3C (+0.2) was on the 16th; at RAF Valley there was a ground frost -1.4C.
Sunshine duration reported by the Met Office at Valley was 206.3h (125%) and [122%] of average (Kipp & Zonen adjusted values), sunniest since 2006 the 14th sunniest June on the Anglesey record since before 1930. The sunniest day was on the 8th having 15.2h. There were 2 sunless days and another 4 had <1 hour. In Llansadwrn sunshine base on the solarimeter reading was 209 h. The mean solar radiation was 18.16 MJ m-2, the highest was 28.34 MJ m-2 on the 8th and the lowest 6.56 MJ m-2 on the 25th when there was the record heavy rain.
 "January to July rainfall anomalies 1929-2008")
Rainfall was 81.5 mm (131%) and [128%] of average, least since 2006 (26.7 mm) as 2007 had 120.4 mm, and ranking 31st wettest since before 1929. It brought the total for the year so far to 679.5 mm, most since 1958 (720.8 mm) and ranking 2nd. The largest fall 17.6 mm was on the 28th. There were 5 days with 5 mm, or more (+0.8). Dry days were 7 (-4.8) while rain days were 19 (+4.3) and wet days 13 (+1.8).
The mean temperature was 15.9C (-0.2) and [+0.3], highest since 2004 with a mean of 17.0C, ranking 9th since before 1979. The highest mean 17.6C was on the 25th and the lowest 7.8C on the 20th . The mean maximum temperature was 19.5C (+0.2) and [0.0], the highest maximum was 26.0C on the 24th (+0.5) and the lowest 13.5C on the 11th (-1.5). The mean minimum was 12.3C (-0.2) and [+0.3) of average. The lowest minimum 7.8C (-0.6) was on the 20th, but the lowest grass minimum 5.2C was the next day, the 21st.
There were 3 days with thunder (+1.9), but no hail was observed.
Sunshine duration at RAF Valley was 166.0 h (100%) and [98%] of the averages, lowest since 2005 that had 158.1 h, but ranking 28 out of 78 on the Anglesey record (Kipp & Zonen adjusted values). The sunniest day was the 27th with 14.5 h, there were 2 sunless days and another 4 days with <1 h . Global solar radiation at Llansadwrn averaged 14.92 MJ m-2 , highest was 25.97 MJ m-2 on the 21st while the lowest was 5.85 MJ m-2 on the 17th. Estimated sunshine duration was 183 h with 4 sunless days.
 "Anglesey sunshine duration in August 1930-2008."){kind=small}
A very dull month, at RAF Valley sunshine duration was 86.2h (54%) and [52%] of average, lowest since before 1930 on the Anglesey record (Kipp & Zonen adjusted value). It was less than in sunny February that had 120.8 h and with only 29 days in the month. Sunniest day was on the 14th with 12.3h and there were 6 sunless days. Global solar radiation at Llansadwrn averaged 11.01 MJ m-2 , highest 21.24 MJ m-2 was on the 2nd and the 25th with 3.90 MJ m-2 had the lowest. There were 8 sunless days.
Rainfall 107.5 mm (115%) and [134%] was lowest since 2006 with 102.3 mm and just behind 2007 that had 108.4 mm). August 2008 ranked 27th wettest in Llansadwrn since 1928. The wettest day was on the 18th with 21.1 mm. There were just 3 (-6.0) completely dry days and 23 (+6.4) rain days (0.2 mm, or more). Wet days, those having 1.0 mm, or more, numbered 19 (+6.8). Days with 5 mm, or more, were 6 were less than average (-0.4). With cloud cover at 09 GMT 93% and relative humidity averaging 91% it was a damp month. On 22 mornings the wind was either S or SW'ly. Easterly component winds were few (NE 2) and (SE 2).
 "Days in August having a temperature of 20C, or more."){kind=small}
The mean temperature 15.5C was (-0.2) and [+0.2] of average and highest since 2005. The mean maximum was 18.1C [(-1.2)] of average and the highest 22.0C on the 6th was one of the 3 to reach 20C, or more, the lowest number in August on record at this station since before 1979. The highest was (-3.9) on the decadal average. The lowest maximum 15.7C was on the 19th and was (+0.6). In contrast the minimum temperature were above average, the mean 12.9C (+0.7) and [+1.5]. Highest was 15.3C, but (-1.1) of average, on the 30th. The lowest 9.8C (+1.5) was on the 22nd. The lowest grass minimum was 7.3C (+2.2) on the 23rd, the above average readings indicative of the many cloudy nights in the month. Soil temperature at 30 cm averaged 16.9C, this (-0.7) of average.
Very wet beginning and end with a dry spell in the middle of the month
A wet month overall with a total of 120.3 mm (106%) and [131%] of the 10-y and 30-y averages. Largest rainfall in September since 2004 (165.8 mm) and 2003 (159.7 mm), ranking 27th wettest since before 1928, it was just 1.6 mm greater than in 2007. The largest fall was on the 5th having 31.1 mm and there were 9 days (+1.6) that had 5 mm, or more. Rain days were 18 (+0.7) and wet days 14 (+0.9), and there were 9 (+0.2) dry days. Evaporation was 34.0 mm measured by Piche evaporimeter and 20.4 mm potential evapotranspiration measured by lysimeter. The potential water balance was 99.9 mm.
; "Monthly rainfall accumlation to end of September 2008 with comparisons."){kind=small}
September's rainfall brought the total for the year so far up to 907.3 mm. This exceeds the total (856.8 mm) at the end of September in Llansadwrn's wettest year in 2000, but was less than 1958 with 992.0 mm and 1957 with 1068.7 mm the only years, since before 1928, to exceed the 2008 January to September total. Both years had wetter Septembers, 1957 with 195.3 mm and 1958 with 175.9 mm (average of 2 stations). The wettest September on record, recorded at Treffos in 1935, was 220.7 mm.
Temperatures were lower than what has been experienced in recent years, but still above the 30-year climatological mean [1971-2000] reflecting the warming trend in our climate. The mean temperature was 13.6C (-1.0) compared with the decadal average, but was [+0.2] compared with the 1971-2000 average. The mean was highest since 2006, just 0.1C greater than in 2007. More significantly it was (with September 2007) lowest since 2001 with a mean of 13.4C. The highest mean was 15.7C on the 11th with 2 other days with 15C, or more, the 13th (15.4C) and 21st (15.5C). The lowest mean was 10.5C on the 29th. Maximum temperatures were rather on the low side, the highest 19.9C on the 26th (-4.4) well below the average of the previous 10-years. The lowest maximum 12.8C (-0.6) was on the 30th. The mean minimum was 10.5C (-0.7) and [+0.8] with the highest 13.5C (-1.9) on the 11th. The lowest minimum of 7.1C (-0.3) and lowest grass minimum were on the 29th. The mean grass minimum was 7.4C (-1.5) and the mean soil temperature at 30 cm depth was 14.9C (-0.4).
Sunshine duration recorded at RAF Valley totalled 124.8 h (98%) and [99%] of the averages using Kipp & Zonen adjusted values. The sunniest day was on the 23rd with 11.1 h duration. There were 4 sunless days.
Rainfall, a total of 282.8 mm was the largest in October, and any month since records began in Llansadwrn in 1928. Exceeding the previous largest of 250.5 mm in November 2000, the wettest year on record, by more than 32 mm. The rainfall was 195% of the average of the past decade, 252% of the 1970-2000 average and 234% of the long-term 1928-2007 average. The wettest day was on the 25th with 52.8 mm that led to local flooding, this was the 2nd highest daily fall in October behind the 86.0 mm on 22 October 2004 that led to flooding in Beaumaris. Two other days had more than 40 mm, the 4th with 41.6 mm and the 14th with 40.3 mm that again led to local flooding. Another very wet day was the 10th with 23.3 mm. Rain days (0.2 mm, or more) totalled 27 (+6.4) while wet days (1.0 mm, or more) were 19 (+2.1). There were 12 (+3.0) days on which 5 mm, or more fell, but the month did have 2 completely dry days and there was just a trace recorded on another 2 days.
It was a wet month in north-west Wales. In Bangor 303.6 mm were recorded, largest since before 1954. The AWS in Llandegai recorded at least 319 mm while on Snowdon, the raingauge at the ECN site at Llyn Llydaw (data courtesy of CCW) recorded over 729 mm. Largest falls were 113 mm on the 25th and 106 mm on the 4th.
Although the first 15 days temperatures were above average ( mean 11.4C +0.8 of 30-year) they ended below average on both the decadal and 30-year averages. The mean 10.0C was (-1.4) and [-0.6] respectively, lowest since 2003 (9.6C) ranking one of the 8 lowest since before 1979. The mean maximum 12.7C was (-1.7) and [-1.1] , lowest since 1993 (12.1C) and ranking 5th lowest. The highest maximum 19.7C (+0.5) on the 12th was just a shade behind the highest maximum of September's 19.9C on the 26th. The lowest maximum on the 28th of 4.5C was (-1.1) of average. The mean minimum of 7.2C was (-1.1) and [-0.1] the latter based on 30-y closest to average of any. Lowest since 2003 (6.5C) and 11th lowest since before 1979. The lowest minimum was 0.0C on the 29th, just missing an air frost, but a ground frost of -3.4C was the lowest of the month. There were 4 ground frosts (+3.0), the largest number since 1997 that had 9, and 5th largest since before 1985. The mean soil temperature at 30 cm depth was 11.7C (-0.8).
Thunder was heard and lightning seen on the 27th; the electricity supply to a large area of SE Anglesey was disrupted for near 4 hours. Large hail fell on 2 days, 7 mm diameter at 0745 GMT on the 3rd, and 8.6 mm diameter just before 2026 GMT on the 27th almost covering the ground. Small hail <5 mm diameter fell on 6 days, these included 2 days that had snow pellets. The small and large hail events numbered 7 and were +6.0 of the average of the last 10 years.
Sunshine duration recorded at RAF Valley totalled 88.4h (provisional) and was (88%) of the decadal and [93%] of the 30-year averages (K&Z adjusted values). The sunniest day was on the 8th having 9.3h. There were 8 sunless days and sunshine was lowest since 2005, ranking 34th on the Anglesey record since before 1930. It was a windy month the mean wind speed was 19.0 mph (124%) and [121%] of average, highest was 36.4 mph on the 23rd. The highest gust was 61 mph on the 23rd and 25th.
A wetter, milder middle of the month. Colder at the beginning and end.
After the record breaking rainfall of October, November was relatively dry with just 98.5 mm (71%) and [79%] of average. Wettest since 2006 (121.6 mm) November ranked 25th driest since before 1928. The wettest day was on the 9th having just 15.5 mm, the only other day to reached double figures (just) was the 17th with 10.0 mm. There were 6 (+2.0) completely dry days while rain days (0.2 mm or more) were 19 (-3.5). Wet days (1 mm, or more) numbered 18 (+0.3) and days with 5 mm, or more, 9 (-0.2).
Average temperatures were lower than those experienced over the past 10-years, but were higher than 30-year climatological series. The mean was 7.7C (-0.5) and [+0.4], this was lowest since 2005 (7.7C) but 12th highest in records since before 1979. The highest mean was 11.5C on the 14th, 2 more days achieved 10C, or more, the 8th with 10.0C and 15th with 11.4C. The mean maximum was 9.7C (-1.0) and (-0.3), lowest since 2000 (wettest year) it ranked 25th lowest since before 1979. The highest maximum was 12.8C on the 14th, the lowest 5.0C on the 30th. The mean minimum was 5.6C (0.0) and [+1.1], lowest since 2005, but ranking 10th highest. The highest minimum was 10.6C on the 15th and 10.1C occurred the previous day (14). The lowest minima were -1.0C on the 29th and -0.2C on the 30th, the only 2 days with air frost (+1.8) the first air frost since 6 April (-0.1C), with 239 frost-free days. Ground frosts were fewer than average numbering just 4 (-3.9). Lowest was -4.6C on the 29th.
Thunder was heard on the 9th and there were 5 days with hail, all ice pellets, this was average for November.
Sunshine duration recorded at RAF Valley totalled 65.3h (114%) and [123%] of average, highest was 8.1h on the 2nd. There were 6 sunless days, and another 7 had <1 hour each day. Here, global solar radiation averaged 4.33 MJ per m2, highest also on the 2nd was 9.30 MJ per m2 while the lowest was 1.54 MJ per m2 on the 17th one of the sunless days at Valley.
The first half wettest with frequent hail, the second colder, drier and sunniest
The month bucked the trend towards warmer and wetter winter months with below average temperatures and rainfall. The mean temperature of 4.6C was below both the decadal (-1.5) and 1971-2000 [-0.9] averages. It was lowest since 1996 and indeed 7th lowest in records since before 1979. The mean maximum was 7.2C (-1.2) and [-0.7] and was 5th lowest since 1979. The highest maximum 10.3C (one of 5 to reach double figures) was on the 22nd was (-2.1) on the decadal average, the lowest maximum 1.6C (-1.5) was on the 30th. The mean minimum 2.0C (-1.7) and [-1.1] again lowest since 1996 and ranking 7th. The highest minimum was 9.4C (+0.1) was on the 22nd while the lowest -3.8C (-1.8) was on the 30th. There were 3 air frosts, all on the last 3 days of the month and there were 22 ground frosts (+8.1) distributed at the beginning and end of the month. While at the beginning the minima were moderate at the end they were much lower with -9.0C recorded on the 30th. The mean of temperature in the soil at 30 cm was 5.4C (-1.3) with 21 days below 5.6C (42F). The soil surface was frozen on 7 mornings and on 1 morning (31) frozen at 4 cm depth (-0.3C).
Rainfall totalled 94.3 mm (71%) and [82%] of average, lowest since 2005, distributed mostly in the first half of the month. The largest fall was 21.0 mm on the 8th followed by 16.2 mm on the 12th. There were just 5 falls of 5 mm, or more (-3.8) and 10 (+3.2) dry days. Rain days totalled 17 (-3.4) and there were 14 days (-2.9) with 1 mm, or more. Rainfall duration was 61.2h with 11.8 h recorded on the 8th and 10.1 h on the 12th.
There was no thunder or snow recorded, but there were 9 days with hail comprising 3 days snow pellets, 5 days ice pellets and 1 day with a rare deposit of ice crystals.
At RAF Valley 63.1 h (138%) of sunshine duration were recorded, this despite 10 sunless days. During the 10-day period 16 - 25th only 2.7h were recorded on 3 of the days, the other sunless. The sunniest day was on the 6th having 6.1h. Valley reported 3 days of gales (4,12 &19) with a maximum gust of 55 mph on the 4th. The month had a mean wind speed 13.0 mph with a maximum of 25.5 mph on the 19th. In Llansadwrn the mean global solar radiation was 2.93 MJ per m2 with a maximum of 6.05 MJ per m2 on the 30th and a minimum of 0.07 MJ per m2 on the 20th.
The mean temperature was 10.2C, lowest since 2001, was below the decadal average (-0.3), but by a similar margin above the 30-y 1971-2000 climatological average [+0.3]. Cooler than years of the last decade, but continuing the general warming trend in comparison with the 30-y average and ranking 13 highest out of the 30-years observations at this station. Only 3 months of the year showed positive anomalies on both averages, January(+0.7) & [+1.6] and February (+0.7) & [+1.3] were remarkably mild while May, the only month to show any summer weather at all, was a remarkable (+1.7) and [+2.1] of average. November was (-0.5) on the decadal, but [+0.4] on the 30-y average. July was the warmest month with a mean of 15.9C while December with a mean of 4.6C was the coolest.
 "Annual mean temperature graph and regression equation."){kind=small}
 "Annual mean temperature anomaly (differences from the 1979-2008 mean)."){kind=small}
The graph shows the mean temperature plotted over the 30-years of station records. Fitted to a linear regression the temperature increases over the period by 1.3C, an indication the warming trend that has taken place. The histogram shows the mean anomaly over the same period (differences from the 1979-2008 mean).
 "No. days in the year exceeding 20C & 25C at Llansadwrn 1979-2008."){kind=small}
At least there were 3 days that reached 25C, or more, there were none in 2007. Days with 20C, or more, were also up numbering 25 in contrast to 2007 that had just 20, both were well behind the 66 recorded in 2006 and 1990, the highest number on record.
The mean maximum of 13.3C, lowest since 2001, was lower than both the decadal (-0.3) and 30-y averages [-0.1] ranking one of the 14 lowest years. Like 2007 maximum temperatures were on the low side. The highest maximum was 26.0C on 24 July and the lowest 1.6C on 30 December.
The mean minimum 7.1C, again lowest since 2001, was (-0.4) on the decadal, but [+0.5] based on the 30-y average ranking one of the 13 highest minima of the last 30 years. There were 14 air frosts through the year, the most 5 were in February, but the lowest minimum was -3.8C on 30 December. There were 83 ground frost, the most 22 were in December that also had the lowest of -9.0C on the 30th.
Total rainfall was 1328.9 (117%) of the last 10-y and [135%] of the 1971-2000 average and 128% of the long-term 1928-2007 average. Rainfall was largest since 2000 in Llansadwrn ranking 4th since before 1928 and 5th largest on the Anglesey record since before 1865. The wettest month was the record breaking October the 282.8 mm being the largest in ANY month in the Llansadwrn records.
Llansadwrn (Anglesey): Monthly weather data for 2008.
Anomaly ~ is based on the 1998-07 average.
Anomaly 30-y is based on the 1971-2000 average.
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
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Air temperatures (C)
Mean max 8.9 10.4 9.8 11.9 17.4 17.2 19.5 18.1 16.6 12.7 9.7 7.2 13.3
Mean min 4.1 2.9 3.3 4.7 9.7 9.7 12.3 12.9 10.5 7.2 5.6 2.0 7.1
Mean 6.5 6.6 6.5 8.3 13.6 13.5 15.9 15.5 13.5 10.0 7.7 4.6 10.2
Anomaly~ +0.7 +0.7 -0.7 -0.9 +1.7 -1.0 -0.2 -0.2 -1.0 -1.4 -0.5 -1.5 -0.3
Anomaly 30-y +1.6 +1.3 -0.2 -0.3 +2.1 -0.1 +0.3 0.2 0.2 -0.6 +0.4 -0.9 +0.3
High max 10.9 16.8 14.6 19.2 25.1 22.8 26.0 22.0 19.9 19.7 12.8 10.3 26.0
Date 13 11 31 22 8 9 24 6 26 12 14 22 24 Jul
Low max 2.5 6.1 6.8 5.7 12.0 13.2 13.5 15.7 12.8 4.5 5.0 1.6 1.6
Date 3 17 22,23 6 17 12 11 19 30 28 30 30 30 Dec
High min 9.4 8.0 6.3 9.7 15.4 13 17.6 15.3 13.5 12.4 10.6 9.4 17.6
Date 21 8 2 26 4 25 25 30 11 10 15 22 25 Jul
Low min -0.5 -1.3 -0.1 -0.1 4.8 6.0 7.8 9.8 7.1 0.0 -1.0 -3.8 -3.8
Date 4 18 18 6 1 13 20 22 29 29 29 30 30 Dec
Grass min -3.7 -7.5 -3.8 -4.4 1.7 3.3 5.2 7.3 0.8 -3.4 -4.6 -9.0 -9.0
Date 12 18 5 8 1 16 21 23 29 29 29 30 30 Dec
Atmospheric moisture means
RH (%) 92 86 84 86 75 78 82 91 88 90 90 92 86
Dew point (C) 5.1 3.0 3.5 5.4 9.6 9.9 12.6 13.5 11.3 7.8 5.8 2.7 7.5
Soil temperatures (C)
5 cm 5.5 4.1 5.5 8.5 15.2 16.6 17.2 16.2 13.6 9.7 6.8 3.6 10.2
10 cm 5.8 4.8 5.6 8.2 13.7 15.2 16.4 15.9 13.5 10.0 7.1 4.2 10.0
20 cm 5.8 5.0 6.2 9.0 14.3 15.7 16.9 16.7 14.6 11.0 7.7 4.5 10.6
30 cm 6.4 5.8 6.9 9.5 14.4 15.8 17.0 16.9 14.9 11.7 8.4 5.4 11.1
Anomaly ~ +1.1 -0.2 -0.4 -0.7 +0.8 -0.3 -0.5 -0.7 -0.4 -0.8 -0.8 -2.1 -0.3
50 cm 6.9 6.6 7.4 9.6 14.1 15.6 16.7 16.9 15.3 12.5 9.2 6.3 11.4
100 cm 7.7 7.5 7.9 9.4 12.9 14.7 15.5 16.2 15.2 13.1 10.3 7.9 11.5
Rainfall (mm)
Rain tot 189.9 68.9 96.1 86.2 33.4 123.5 81.5 107.5 120.3 282.8 98.5 94.3 1382.9
Rain % ave~ 168 74 131 110 48 168 131 115 106 195 71 71 116.5
Rain % 30-y 194 92 113 149 58 186 128 134 131 252 79 82 134.6
Days, dry 6 10 4 5 17 13 7 3 9 2 6 10 92
Days >=0.2 23 14 22 21 11 16 19 23 18 27 19 17 230
Days >=1.0 20 11 18 18 9 12 13 19 14 19 18 14 185
Days >=5.0 12 5 6 7 1 6 5 6 9 12 9 6 84
Max fall 48.8 16.3 20.6 11.0 8.3 40.7 17.6 21.1 31.1 52.8 15.5 21.0 52.8
Date 9 29 15 12 4 26 28 18 5 25 9 8 25 Oct
Evaporation
Piche (mls) 21.6 35.7 41.7 35.1 72.3 49.3 45.2 31.2 34.0 35.2 27.8 19.0 448.1
Lysimeter PE (mm) -4.7 10.3 19.6 37.5 70.3 69.3 57.8 24.4 20.4 4.5 3.5 3.3 316.2
Weather (days)
Air frost 2 5 1 1 0 0 0 0 0 0 2 3 14
Ground fr 12 19 11 11 0 0 0 0 0 4 4 22 83
Sl/snow 1 0 6 3 0 0 0 0 0 1 0 0 11
Sn lying 0 0 0 0 0 0 0 0 0 0 0 0 0
Thunder 0 0 0 0 1 0 3 0 1 1 1 0 7
Hail <5 mm 9 3 12 8 0 1 0 0 1 7 5 9 55
Hail >=5 mm 0 0 0 0 0 0 0 0 0 1 0 0 1
Fog at 09h 1 1 0 0 0 0 0 0 0 0 0 1 3
Gales 8 3 3 0 0 1 0 0 0 5 1 3 24
Wind direction at 09h (days)
N 0 0 5 4 0 2 3 1 5 1 4 0 25
NE 1 3 4 3 15 5 1 2 3 3 6 6 52
E 2 5 1 7 6 0 2 0 2 1 1 5 32
SE 1 0 0 1 5 1 4 2 5 1 0 1 21
S 12 5 4 5 4 9 11 12 9 6 1 4 82
SW 8 10 8 8 1 10 4 10 4 6 8 7 84
W 5 3 7 0 0 1 3 2 2 9 3 1 36
NW 1 1 2 0 0 2 1 0 0 4 6 3 20
Calm 1 2 0 2 0 0 2 2 0 0 1 4 14
Autographic records of rainfall and frost duration (h)
Rain 127.0 45.6 72.8 81.2 32.3 64.0 51.4 92.6 101.0 158.3 70.3 61.2 957.7
Frost 7.5 27.6 0.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 7.2 48.3 90.8
Cloud cover at 09 GMT
Mean (%) 83 62 76 81 61 79 81 93 68 75 78 70 76
Global solar radiation (MJ m-2) and sunshine duration (h)
Llansadwrn
Sol rad mean 1.68 6.10 9.35 13.92 18.74 18.16 14.92 11.01 9.87 8.21 4.33 2.93 9.94
Maximum 4.85 10.95 17.52 23.20 27.86 28.34 25.97 21.24 17.53 14.92 9.3 6.05 28.34
Date 24 19 17 16 19 8 21 2 1 12 2 30 8 Jun
Minimum 0.05 1.48 3.07 5.36 6.02 6.56 5.85 3.9 3.63 2.31 1.54 0.07 0.05
Date 23 29 20 20 28 26 17 25 6 10 17 20 23 Jan
* ESD (h) 51 90 125 168 221 209 183 143 129 111 75 63 1567
Sunless days 14 6 8 7 4 2 4 8 5 8 9 10 85
Valley
Sunshine (h) 42.7 120.8 127.8 168.2 232.3 206.3 166.0 86.2 124.8 88.4 65.3 63.1 1491.9
Average % ~ 69 153 104 105 125 125 100 54 98 88 123 138 104
Sunniest 5.7 9.1 10.7 11.3 15.2 15.2 14.5 12.3 11.1 9.3 8.1 6.1 15.2
Date 3 18 17 16 31 8 27 14 23 8 2 6 8 Jun
Sunless days 11 7 5 3 2 2 2 6 4 8 6 10 66
# C-S (h) 45.8 129.2 137.9 189.2 275.9 250.1 199.3 101.3 143.0 99.1 71.6 68.0 1710.2
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Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Year
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I am grateful to Robert Jones, former Observer/ Admin. Officer, and Geraint Roberts at the Met Office RAF Valley, for supplying Valley data. Thanks also to Alex Turner, Environmental Change Network Project Officer, Countryside Council for Wales, for making available Snowdon data. I am also grateful to Ivor Mclean of Bangor for his personal communication.
#. Valley sunshine duration, since August 2005, has been measured using a Kipp & Zonen electronic sensor. This gives sunshine durations that are different to the previous Campbell-Stokes instrument. A conversion factor 1 has been applied to estimate what the Campbell-Stokes (C-S) duration might have measured for comparison. The electronic sensor measures less sunshine than the Campbell-Stokes instrument, it varies throughout the year and is about 20% less in summer and 7% less in winter. Averages have been computed using estimated equivalent Kipp & Zonen sunshine durations.
References
1: Prior J. (2006). Sunshine measurement. Weather 61, p. 77.
2: Kerr A. & Tabony R. (2004). Comparison of sunshine recorded by Campbell-Stokes and automatic sensors. Weather, 59 (4), pp. 90-95.
* ESD is an experimental Estimated Sunshine Duration. It was calculated using a relationship derived by fitting Llansadwrn global solar radiation and Valley sunshine duration data to a linear regression equation.
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These pages are designed and written by Donald Perkins © 2008 Page first dated 2 February 2008 http://www.llansadwrn-wx.co.uk
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