Llansadwrn (Anglesey) Weather
Monthly summary for 2000
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Llansadwrn (Anglesey) Weather
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A relatively mild month with a mean of 5.7C (+0.4). Highest maximum (10.7) was on the 5th while the lowest minimum (0.1C) was on the 16th. There was no air frost, the only other January in records with none was 1990. It was a wet month with 145mm rain; the highest fall of 40.6mm was on the 11th. This was the wettest day since the fall of 40.7mm on 10 January 1984. A windy month with 5 days of gales. On the 7th VALLEY (Anglesey) was reporting gusts of 61 mph. On 11th a Scottish trawler seeking shelter off the Isle of Man was lost with 7 crew aboard. Irish Sea ferries were seriously delayed or cancelled on many days in the month.
Another wet month with 143mm rainfall. The most in a day was 25.4mm on the 27th but there were falls of 12.6mm on the 3rd; 14.7mm on the 9th; and 14.7mm on the 11th. This was 196% of the long-term average but only 156% of the 10-y 1990-99 average. Number of wet days (1mm or more) were 21 (+7) and there were 11 days of 5mm or more (+4). It was the 7th wettest February in records since 1928 and contributed to making it the 4th wettest winter (December 1999- February 2000) on record with 482mm. Other wet winters have been 1959/60 (493 mm), 1989/90 (493 mm) and 1994/95 (510 mm). Three of these occurring in last 11. Temperatures continued to be a little above average with the mean 6.2C (+0.6). There was 1 air frost of -0.4C on the 20th and there were only 5 this winter, and was the least number on record since 1979. There were 12 ground frosts (+0.8).
Except for strong winds on the 2nd it was a quiet month with no gales. It was the fourth mild March in succession with a mean of 7.3C. The absolute maximum of 13.6C was the lowest in March since 1995. There were frequent ground frosts (12) and was the highest number since 1996. It was a cloudy month, the 13-21st being sunless, but was redeemed by the 22nd, 24th and 27th which were almost cloudless. Rainfall 54.3mm was 65% of average, 75% of the long-term average. There were depositions of a pink or orange dust on the 3rd, 10th, 13th, 17th and 23rd probably of Saharan origin.
Mean temperatures were running well below the daily average from 1-19th, anomaly of -4.6C on 3rd and -4.3C on 17th. There was a warm spell from 20-26th when means had an anomaly of up to +3.1C. Two colder days 27-28th (-1.0C) were a prelude to the warmest day on the 30th (mean 11.3C, +1.0C). The monthly mean was 7.8C (-1.1C). Maximums were low, the lowest (3.5C) on the 3rd being the 3rd coldest and the highest 16.5C on 30th, was the 5th lowest on record. The mean min (4.5C) was the coldest since 1994. In the last decade there have been only 2 colder Aprils while there were 8 in the previous decade. There were 7 falls of small hail (+4.7) and sleet or snow was seen on 4 days (+2.3). Rainfall (78.8mm) was 12% above average, 30% above the long-term average.
It was a very warm and dry start to May. The mean of the first 15 days (13.7C) was the warmest on record (since 1979) beating 1990 by 0.2C. With only 0.2 mm on the 12th it was the driest since 1984 (1.0 mm). Completely dry starts to May occurred in 1980, 1941 and 1928. The second half of the month was a complete contrast, with below average temperatures and above average rainfall. There have been only 3 wetter ends of May in the last 20y. The driest May on record (since 1928) in Llansadwrn was 1939 with 19.0 mm.
Split-month temperature (ºC) and rainfall (mm) means with differences from my 1979-99 average.
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Dates |
Max |
Diff |
Min |
Diff |
Mean |
Diff |
Rain |
Diff |
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1-15 |
17.8 |
+2.4 |
9.5 |
+3.4 |
13.7 |
+2.9 |
0.2 |
-28.4 |
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16-31 |
13.6 |
-2.8 |
6.6 |
-1.4 |
10.1 |
-2.1 |
53.0 |
+22.0 |
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Month |
15.6 |
-0.3 |
8.0 |
+0.9 |
11.8 |
+0.3 |
53.2 |
-6.4 |
The spring months (March-May) had a mean maximum of 12.3C (+0.7) and mean minimum of 5.6C (0.0). Rainfall of 186.3mm was below average (87%). It was the driest spring since 1997 (171mm) but there have been 30 drier ones in records since 1928.
June was a dry month and with 41.0mm was the driest since 1996 (40.5mm). In records dating back to 1928, it was the 16th driest June and was in contrast to the Junes of 1997, 1998 and 1999 each of which had over 100mm. It is necessary to look back to 1942 to find the driest June which had only 8.4mm. There was a lot of cloud at times and this, with several windy days (1, 11-12, 19 & 21) and sea breezes, resulted in moderate maximum temperatures and a mean of 17.2C (-0.1), but was the warmest since 1996 (17.6C). An exception was on the 18th when there was a maximum of 29.0C, this was the earliest date in the year by which such a temperature has been recorded since records began in 1979. As a result of the cloudy nights, which minimised cooling, the mean minimum temperature was 10.6C (+0.9C). This was the second warmest June mean minimum in records since 1979 (warmest was 1982 with a mean of 10.8C). The warmest night was on the 19th with a minimum of 15.1C. The lowest maximum was on the 9th (13.0C at 0900 GMT on the 10th), but the temperature during the day on the 9th reached only 9.5C. The lowest minimum (7.0C) was the 2nd warmest in the records (1992 had 7.5C) and the grass minimum (4.0C) on the 10th was the 4th warmest recorded. The mean (13.9C) was the warmest since 1993 (14.5C) but only the 7th warmest in records. There was no thunder or hail recorded during the month.
July had 16 dry days including a spell 14-25th (included 2 days recording trace amounts). Rainfall for the month was 69.9mm but included 6 days with 5mm or more. These 6 days accounted for 56.6mm, or 81% of the month's rain. The impression was that it was a dry month, the grass beginning to look a bit brown in places where the soil is shallow over underlying rock. Roadside verges were also looking very dry around the island. Rainfall was 95% of the 1961-90 average, but was 126% of the COL 10-year average; the average distorted because the last decade has been relatively dry. The wettest day was the 29th with 18.8mm which fell in only 0.7h; most (16.2mm) fell over 12-15 minutes, a rate of about 65mm per hour. In contrast the next largest fall of 13.5mm, on the 9th, fell over a period of 9.0h.
Temperatures were rather on the cool side with a mean maximum of 18.5C (-1.2C). The warmest day was on the 19th with 22.1C. Minimum temperatures (mean 11.7C) were -0.4C of average; there were 4 warm nights of 14C or more. The lowest minimums (8.5C) were on the 17th and 18th while the lowest grass minimum (5.7C) was on the 12th. For the second month in succession no thunder or hail was recorded. Sunshine was above average with Valley reporting 231h sunshine for the month.
; "Click for October rainfall histogram 1928-2000."){kind=small}
Only 1967 that had 259mm, recorded at Gadlys Cottage, and 1954 that had 249mm at Treffos exceeded this October's total. There were some very wet days with the 29th having 35.8mm, the wettest October day since 36.6mm in 1991, and the 26th with 29.6mm. Six days exceeded 10mm and 16 days had more than 5mm. The number of wet days 23 (+7.7) and rain days 29 (+10.6) were the most recorded at this site since records began in 1979. There was only 1 dry day, the 21st! The January-October total of rainfall is 1080mm and is the wettest since 1967 (1107mm) and the 4th wettest in the Llansadwrn records.
Yet again another very wet month. With 250.5mm (217% of average; 203% of the 1961-90 climatological average) it was the wettest November on record since 1928. It was also the second wettest month, any month, in the records. The wettest month with 259mm was recorded at Treffos in October 1967. ; "November rainfall histogram 1928-2000."){kind=small}
There were some very wet days with the 5th having 30.4mm and the 13th with 25.2mm. Some rain fell every day in the month, there were no dry days. In the record holding 1967 there were 2 dry days! The number of rain days 28 (+6.5); wet days 26 (+9.7); and days of 5mm, or more, 18 (+10.0) were all the most recorded at this site since records began in 1979. The rainfall duration (0.1mm per hour, or more) was 184.3h. The January-November total is 1340mm, this is the wettest in the records, beating 1954 that had 1324mm.
Air temperatures, like October, were all below average. The mean maximum was 9.4C (-1.0) and the mean minimum 4.7C (-0.4), this gave the mean of 7.0C an anomaly of -0.7C. The maximum for the month was 16.7C on the 28th. This occurred between 2000-2100 GMT during a Föhn wind from the Snowdonia Mountains, a SSE'ly force 7 to gale 8. During this event the relative humidity dropped to 54%, the lowest in a month of otherwise high values (average 92%). At Abergwyngregyn (Gwynedd) 18.0C was recorded, the highest temperature recorded on this date in the UK. Despite the wetness there were sometimes clear periods at night that allowed the temperature to fall sufficiently to give 14 ground frosts. The lowest was -3.1C on the 15th that also had the lowest minimum of 2.6C. The mean grass minimum of 1.2C was -1.5C of average. Cloud at 0900 GMT averaged 6.9 oktas, or 87%. At Valley on 40.3h of sunshine were recorded (63% of average) while at Abergwyngregyn it was even duller with only 12.5h.
It was again a windy month with gales on 5 days. The mean monthly wind speed at Valley was 19mph; the maximum gust of 69mph was on the 25th with 2 others on the 29-30th recording over 50mph.
There were 2 heavy thunderstorms. On the 1st during which there was a fall of 10mm diameter hail and on the 5th when there was a 10-min spell of 5mm hail and rain during which the temperature fell 5C. On 9 other days there were falls of ice pellets and sleet was observed on the 20th.
A wet month with 153.6mm rainfall (125% of average; 136% of the 1961-90 climatological average). Unlike previous months, it did not break any records as it was only the 14th wettest in records since 1928! Last December was much wetter with 194mm and 1994 had 205mm. The month even had 3 dry days and the largest fall of 19.7mm on the 7th did not even reach an inch (25mm). The number of rain days 24 (+4.1); wet days 21 (+5.3) and days with 5mm. or more, 12 (+3.3) were however all above average. Rainfall duration (0.1mm per hour, or more) was 94.2h. The month's rainfall brought the total for the year (Jan-Dec) 2000 to 1484mm, the largest on record since 1928, beating the previously wettest year of 1954 that had 1452mm. In the latter part of the month the weather turned cold and 17.7mm fell as dry snow on the 27th. The snow was lying on average 18.5cm deep on the 28th and lasted for 4 days before a rapid thaw set in.
Despite the cold spell at the end of the month mean air temperatures were above average. The mean maximum was 8.4C (+0.5) and the mean mimimum 3.9C (+1.0), this gave the mean of 6.2C an anomaly of +0.8c. For the first 12 days maximum temperatures were all 10C, or more, except on the 8th that dropped to 8.9C. During this spell the lowest minimum recorded was 6.2C and there were no ground frosts. ; "Mean temperature graph 2000."){kind=small}
All these temperatures were above the average for December. From the 13th onwards the weather was cooler with ground frost (-3.6C) on the 16th and the first airfrost (-0.5C) of the winter on the 16th. A much colder cold spell starting on Boxing Day (26th) brought a succession of airfrosts (lowest -4.7C on the 29th) and severe ground frosts (lowest -10.6C also on the 29th above snow). The maximum temperature on the 28th just reached 0.7C for a while but at Pentraeth it remained below zero all day. For 2 days the mean temperatures were below zero, -1.5C on the 28th and -0.9C on the 29th.
It was another windy month with 7 days with gales, 6 in the first 13 days of the month. But there were periods of much calmer weather and there were 5 days when it was calm at 0900 GMT. Cloud at 0900 GMT averaged 6.2 oktas (78%); on the 22nd the sky was cloudless, a rare event.
Thunder was heard on 2 days, the 10th and 30th. There were 11 days with hail (all types) +5.9 of average. These included falls of minute elongated ice crystals (h1) and snowgrains (h2) on Christmas Day (25th); snow pellets (soft hail) on the 26th, 27th and 29th. Ice pellets fell on 8 days (3, 13-16, 27, 29 and 31). Hail (5mm) fell on the 13th. Sleet or snow fell on 7 days (16, 26-31) with snow lying up to 20 cm deep on 4 days (28-31).
Millennium year 2000 will go into the record books as the wettest year since records began in Llansadwrn in 1928. With a total of 1484mm (1036-h duration) it beat the previously wettest year of 1954 that had 1452mm. ; "Annual rainfall histogram 1929-2000."){kind=small}
Eight months of the year had above the long-term average; these were January, February, April, and August- December. The wettest month was November with 251mm (205% LTA), itself a record, being the wettest November in the records beating the 246mm recorded at nearby Treffos in 1960. November also nearly had the distinction of being the wettest month of any, but it was piped at the post by October 1967 with 259mm. November with 184-h had the largest rainfall duration closely followed by October with 138h. The 4 months with below average rainfall were March, May, June and July. The driest was June with 41mm (57% LTA), was the 16th driest June in the records, and had 46-h rainfall duration. ; "Monthly rainfall histogram 2000."){kind=small}
The number of rain days (0.2mm or more) was 242 (+39); wet days (1.0mm or more) 192 (+38) and days with 5mm, or more, 107 (+36) gives an indication of the year's wetness. There were, however, 84 days on which not a drop of rain was recorded! Relative humidity was generally high with an average of 87%. The most humid month was November with 92% and the least humid was May with 78%. Cloud cover at 0900 GMT averaged 6.0 oktas, or 76%. Most cloudy was November with 6.9 oktas (87%) and the least cloudy month was May with 4.8 oktas (60%).
There were 19 days (+7) in the year when sleet or snow was seen to fall. Most (7) occurred in December but there were 4 in April. The year with most was 1995 with 35 days and there were none in 1992 (in records back to 1979). Snow was lying on only 4 days (+1), these being on 28-31 December. The most number of days with snow lying (10) was in 1985. The number of days with all types of hail was 45 (+23). This is the largest number on record. There were 5 days when hail or 5mm, or more, were observed including 10-15mm diameter hailstones on 20th August. Thunder was heard on 12 days during the year (+4) with August being the most thundery with 4 days. In records since 1979 the most thundery month was May 1983 with 5 days.
Article: An analysis of the autumn's rainfall.
Complete weather diary for 2000.
Complete daily weather observations.
Llansadwrn (Anglesey): Monthly weather data for 2000.
(~ Based on the 1990-99 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 7.8 8.9 10.3 11.0 15.6 17.2 18.5 19.1 17.6 13.3 9.4 8.4 13.1
Mean min 3.5 3.4 4.3 4.5 8.0 10.6 11.7 12.3 11.1 7.2 4.7 3.9 7.1
Mean 5.7 6.2 7.3 7.8 11.8 13.9 15.1 15.7 14.3 10.3 7.0 6.2 10.1
Anomaly~ +0.4 +0.6 0.0 -1.1 0.0 +0.4 -0.8 -0.3 +0.7 -0.5 -0.7 8.2 -0.1
High max 10.7 12.8 13.6 16.5 24.1 29.0 22.1 24.7 24.3 18.8 16.7 13.2 29.0
Date 5 14 13 30 14 18 19 25 11 3 28 4 18 Jun
Low max 5.2 5.5 8.2 3.5 10.5 13.0 14.1 16.5 13.8 9.5 6.5 0.7 0.7
Date 14 16 1,3 3 26 9 10 4,31 20 29,30 22 28 28 Dec
High min 8.5 8.3 8.8 9.4 12.5 15.1 14.5 15.9 16.2 10.5 11.1 10.5 16.2
Date 31 1 9 20 13 19 22 14 11 2 29 7 11 Sep
Low min 0.1 -0.4 -1.6 0.5 4.4 7.0 8.5 8.8 6.1 2.9 2.6 -4.7 -4.7
Date 16 20 4 16 29 10 17,18 20,29 19 30 15 29 29 Dec
Grass min -3.0 -4.6 -5.8 -3.7 1.3 4.0 5.7 6.2 2.2 -0.9 -3.1 -10.6 -10.6
Date 16 20 4 6 29 10 12 18 19 31 15 29 29 Dec
Soil temperatures (C)
5 cm 4.6 4.8 6.8 7.9 13.7 15.7 17.4 16.3 14.5 9.8 6.3 5.2 10.3
10 cm 4.9 5.2 6.9 7.6 12.9 15.0 16.8 16.1 14.5 10.3 6.8 5.7 10.2
20 cm 5.3 5.8 7.5 8.4 13.4 15.1 17.2 16.8 15.2 11.3 7.5 6.3 10.8
30 cm 5.5 6.3 8.0 9.1 14.0 15.4 17.5 17.5 15.9 12.1 8.0 6.8 11.3
50 cm 6.1 6.7 8.2 9.2 13.7 15.0 17.2 17.5 16.2 12.7 8.7 7.6 11.6
100 cm 6.9 7.3 8.2 9.1 12.5 14.0 16.0 16.6 15.8 13.3 9.8 8.5 11.5
Rainfall (mm)
Rain tot 145.2 143.4 54.3 78.8 53.2 41.0 69.9 132.4 138.6 223.0 250.5 153.6 1483.9
Rain % av~ 140 156 66 112 85 60 126 200 153 193 217 125 142
Days, dry 6 5 11 7 15 8 14 6 8 1 0 3 84
Days >=0.2 23 23 15 18 14 15 14 20 19 29 28 24 242
Days >=1.0 15 21 10 14 9 10 11 15 17 23 26 21 192
Days >=5.0 6 11 3 7 6 3 6 9 10 16 18 12 107
Max fall 40.6 25.4 15.8 13.1 8.3 9.5 18.4 25.2 32.2 35.8 30.4 19.7 40.6
Date 11 27 2 2 17 2 29 2 19 29 5 7 11 Jan
Evaporation (mm)
Piche 21.4 27.4 29.3 40.0 55.3 42.3 39.6 35.3 33.5 33.3 24.7 26.9 409.0
Lysimeter -8.5 -4.5 18.8 16.8 63.7 48.8 62.4 33.2 16.1 17.8 -4.6 -11.4 248.6
Weather (days)
Air frost 0 1 1 0 0 0 0 0 0 0 0 7 9
Ground fr 13 12 12 8 0 0 0 0 0 3 14 12 74
Sl/snow 2 2 1 4 0 0 0 0 0 2 1 7 19
Sn lying 0 0 0 0 0 0 0 0 0 0 0 4 4
Thunder 1 1 0 0 1 0 0 4 0 1 2 2 12
Hail <5mm 3 4 3 7 2 0 0 1 0 1 9 10 40
Hail >=5mm 0 0 0 0 1 0 0 1 0 0 2 1 5
Fog at 09h 0 0 1 0 0 0 0 1 0 0 0 0 2
Gales 5 6 0 0 0 0 0 0 1 5 4 7 28
Wind direction at 09h (days)
N 6 1 1 3 3 0 4 0 2 2 1 2 25
NE 3 0 4 13 9 9 11 6 2 0 4 0 61
E 0 0 2 0 1 0 1 1 2 0 0 4 11
SE 0 1 1 0 1 1 0 0 4 1 3 2 14
S 5 6 2 6 8 5 3 7 5 10 4 10 71
SW 8 9 11 5 3 10 4 9 9 5 8 6 87
W 3 7 2 0 1 1 2 4 1 6 4 0 31
NW 2 4 5 0 4 2 3 2 3 6 6 2 39
Calm 4 1 3 3 1 2 3 2 2 1 0 5 27
Autographic records of rainfall and frost duration (h)
Rain 89.7 91.2 47.9 89.7 62.3 46.4 49.1 56.3 86.8 137.8 184.3 94.2 1035.7
Frost 0.0 8.5 5.4 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 72.6 86.5
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These pages are designed and written by Donald Perkins © 2000Page dated 1 February 2000http://www.llansadwrn-wx.co.uk
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