Climatology at Llansadwrn

Recording Raingauge.
Llansadwrn (Anglesey) Weather

Climatological Averages and Extremes
Logo: Llansadwrn Weather - Melin Llynnon, Ynys Môn.

Introduction
Monthly averages for the past 10 years
Extremes of rainfall and temperature
Rainfall averages 1981-90
Temperature averages 1981-90
Weather averages 1981-90

Introduction

Rainfall has been recorded at Llansadwrn since 1928. Records were made at Treffos, about 680 m southwest of the present site, from 1928 until 1978. It was also recorded at Gadlys Cottage, about 360 m west of the present site, from 1946 until 1974. I began observations at the present site when I realised that the long rainfall record had ended because the then recorder had moved from the village. It seemed a good idea to continue the rainfall observations and, as the previous sites had been approved stations, I offered my services as rainfall observer and the Meteorological Office agreed. Opportunity was taken to commence other observations at the new site.

In the period 1994-2003 the mean annual rainfall is 1083 mm, the wettest months are October to December and the driest April and May. There are on average 206 rain days (0.2 mm, or more) and 157 wet days (1.0 mm, or more) each year. The number of days with 5 mm, or more, are 75 but only 4 days on average each year have 25 mm or more. With all this rain we do, believe it or not, have 112 completely dry days in the average year. Even in the year 2000, the wettest year on record, we had 83 dry days.
The mean annual maximum temperature is 13.5 C and mean minimum 7.1 C. The warmest months are July (mean 15.8 C) and August (mean 16.1 C) and the coldest December (mean 5.6C) and January (mean 5.4 C). Anglesey is relatively mild and frost-free, at Llansadwrn there has been an average of 18 days with air frost ( we only had 7 in 2002 the lowest on record) and 71 days with ground frosts each year. Sleet or snow is rare averaging 14 days a year with snow lying on the ground for only 3 days. Hail (all types) falls on average 29 days a year while thunder is heard on 8 days a year.

Monthly averages for the past 10 years

Llansadwrn (Anglesey): Means for the 10-y period 1998-2007

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                  Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec    Year
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Air temperatures (C)

Max               8.2   8.6  10.5  12.8  15.6  17.7  19.3  19.3  17.8  14.4  10.7   8.4    13.6
Min               3.4   3.2   4.0   5.5   8.2  11.3  12.9  12.2  11.2   8.3   5.6   3.7     7.5
Mean (Tx+Tn)/2    5.8   5.9   7.3   9.2  11.9  14.5  16.1  15.8  14.5  11.4   8.2   6.1    10.5
Highest max      12.0  12.4  16.5  18.6  23.4  25.2  25.5  25.9  24.3  19.2  15.1  12.4    28.1
Lowest max        4.0   4.3   5.8   7.4  10.6  13.2  15.0  15.1  13.4  10.4   6.6   3.1     2.4
Highest min       9.0   8.3   8.9   9.8  13.2  15.0  16.0  16.4  15.4  12.5  10.9   9.3    17.2
Lowest min       -1.6  -1.3  -1.9   0.4   3.7   5.9   8.4   8.3   6.8   3.9   1.1  -2.0    -3.3
Grass min         0.8   0.7   1.5   3.1   6.2   8.9  10.4  10.2   8.9   5.6   2.7   0.7     5.0
Lowest grass     -5.8  -5.8  -6.4  -3.1   0.3   3.1   5.4   5.1   3.3   0.0  -3.3  -6.7    -8.5


Soil temperature (C)

30 cm             5.2   6.0   7.3  10.2  13.7  16.1  17.5  17.6  15.2  12.5   9.2   6.6    11.4

Rainfall

Rain (mm)       113.0  93.7  73.5  78.4  70.3  73.4  62.1  93.1 113.9 144.8 138.3 132.3  1186.8
Days, dry         7.0   6.2   9.6   9.3  11.4  10.4  11.8   9.0   8.8   7.4   4.0   6.8   101.7
Days >=0.2       20.0  18.0  16.3  17.2  16.1  15.7  14.7  16.6  17.3  20.6  22.5  20.4   215.4
Days >=1.0       15.5  13.5  11.3  13.9  11.9  10.9  11.2  12.2  13.1  16.9  17.7  16.9   165.0
Days >=5.0        7.3   6.2   4.5   5.6   4.8   5.1   4.2   6.4   7.4   9.0   9.2   9.8    79.5
Days >=10.0       3.6   3.0   2.4   2.3   1.8   1.9   1.7   3.0   3.7   4.8   4.7   4.3    37.2

Weather (days)

Air frost         3.7   3.1   2.7   0.6                                       0.2   3.6    13.9
Ground fr        11.7  13.5  11.3   6.1   0.7                           1.0   7.9  13.9    66.1
Sl/snow           1.4   3.3   2.2   1.9   0.1                           0.3   1.0   1.9    12.1
Sn lying          0.0   0.7   0.8   0.1                                       0.1   0.9     2.6
Thunder           0.5   0.2   0.3   0.2   0.8   0.9   1.1   1.6   0.8   0.9   1.0   1.0     9.3
Hail (all)        4.5   5.9   4.4   4.1   1.3   0.3   0.1   0.4   0.4   2.0   5.0   6.0    34.4

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Rainfall and temperature extremes


Llansadwrn (Anglesey): Extremes of Rainfall and Temperature

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RAINFALL 1928-2006

Wettest year        2000                  1484 mm
Driest year         1945                   787 mm
                    
Wettest month       October 2008           283 mm
Driest month        January 1997             7 mm

Wettest day         10 August 1957         137 mm

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TEMPERATURE 1979-2006

Warmest year        2006                   10.8 C
Other warm years    1990, 1997, 2003, 2007 10.7 C
Coolest year        1979                    8.9 C

Highest maximum     19 July 2006           34.9 C
Lowest maximum      12 January 1987        -2.3 C

Highest minimum     2 August 1995          19.6 C
Lowest minimum      12, 13 February 1985   -8.0 C

Lowest grass min.   3 March 2006          -12.4 C

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The following tables appeared in 'Climatological Averages and Extremes for periods from 1961 to 1990'
published by the Climatological Observers Link.

Rainfall averages 1981-90


Llansadwrn (Anglesey): Rainfall averages 1981-90

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                     Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec   Year
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Mean               102.4  66.6 102.8  47.0  50.5  63.7  64.0  94.6  87.9 125.7 111.6 122.9 1039.8
Wettest            182.6 180.5 205.9  82.4  86.6  90.4 111.6 154.5 149.7 197.6 172.4 201.4 1117.9
Driest              26.7  15.5  18.3  11.7  22.8  19.8  19.2  46.6  11.7  63.0  38.9  61.9  932.4
Mean raindays       22.3  14.4  19.4  14.0  14.5  15.4  13.1  17.6  15.9  20.5  19.2  20.4  206.7
Max raindays          28    24    26    22    24    22    23    30    24    27    27    27    230
Mean wetdays        16.6  10.9  14.4  10.0   9.7  10.8   9.2  12.7  11.5  16.0  15.4  15.6  152.8
Max wetdays           24    22    22    19    16    17    17    20    17    20    24    21    162
Mean max 24-h fall  20.6  16.4  23.0  14.7  14.6  16.7  21.0  23.7  18.1  24.4  23.8  26.5   39.3
Wettest day         40.7  26.3  69.1  33.8  31.0  32.0  36.8  37.0  31.4  33.6  37.6  44.2   69.1
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Temperature averages 1981-90

 
Llansadwrn (Anglesey): Temperature averages 1981-90

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                       Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec   Year
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Mean max               7.3   8.4  10.4  13.3  16.4  18.0  19.9  19.2  17.0  13.8  10.0   7.8   13.5
Mean min               2.2   1.4   3.2   4.0   6.9   9.6  11.7  11.4   9.6   7.2   4.2   2.8    6.2
Mean                   4.8   4.9   6.8   8.7  11.7  13.8  15.8  15.3  13.3  10.5   7.1   5.3    9.9
Warmest month          6.8   7.1   8.3  10.6  13.4  15.0  17.9  17.2  14.1  11.9   7.9   7.4   10.7
Coldest month          1.8   1.7   5.7   6.8  10.5  12.4  14.1  13.2  11.9   8.2   5.3   2.4    9.0
Highest maximum       11.3  17.2  20.0  24.0  27.6  26.8  28.8  33.0  26.4  24.5  16.8  12.8   33.0
Mean monthly highest  10.8  13.4  15.2  19.5  22.3  23.6  25.5  26.0  23.1  20.2  14.4  10.9   27.6
Mean monthly lowest   -2.9  -3.6  -2.1  -1.1   1.9   5.0   7.1   7.3   5.1   2.2  -1.1  -2.9   -5.0
Lowest minimum        -7.5  -8.0  -5.2  -3.1  -0.1   2.8   5.6   5.6   3.2  -0.8  -3.3  -6.6   -8.0
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Weather averages 1981-90

 
Llansadwrn (Anglesey): Weather averages 1981-90

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                    Jan   Feb   Mar   Apr   May   Jun   Jul   Aug   Sep   Oct   Nov   Dec   Year
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Mean air frost      7.6  11.1   3.8   2.1   0.1   0.0   0.0   0.0   0.0   0.3   2.5   8.1   35.6
Max air frost        20    24    11     4     1     0     0     0     0     2     7    20     53
Mean snow falling   3.9   3.1   2.2   1.4   0.1   0.0   0.0   0.0   0.0   0.1   0.8   2.6   14.2
Max snow falling     12     6     5     4     1     0     0     0     0     1     5    10     29
Mean snow lying     1.8   1.0   0.3   0.2   0.0   0.0   0.0   0.0   0.0   0.0   0.2   1.3    4.8
Max snow lying        7     3     2     1     0     0     0     0     0     0     2     9     11
Mean thunder        0.3   0.3   0.1   0.2   1.1   1.1   0.6   1.1   0.3   0.4   0.5   0.3    6.3
Max thunder           1     2     1     1     5     3     4     3     1     2     3     2     16
Mean hail           1.9   0.7   1.3   0.5   0.5   0.1   0.0   0.1   0.2   0.2   1.2   1.2    7.9
Max hail              5     2     5     2     2     1     0     1     1     1     3     4     16
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Llansadwrn (Anglesey) Weather Climatological Averages and Extremes