May 2009
Burgh Island, Devon at high tide on a warm May evening.
Burgh Island, Devon at high tide on a warm May evening.
Summary for  May 2009
Mean Max: 17.9ºC (+1.8ºC)
Mean Min: 8.3ºC (+0.9ºC)
Mean: 13.1ºC (+1.3ºC)
     
High Max: 25.9ºC 31st
Low Max: 12.6ºC 15th
High Min: 12.1ºC 28th
Low Min: 3.3ºC 4th
Mean Grass Min: 5.6ºC  
Grass Min: 0.4ºC 4th
     
Rain Total (gauge): 49.4 mm (87%)
Rain Total (tipping bucket): 48.1 mm (85%)
Rain Days >0.2 mm: 11 Days  
Rain Days >1.0 mm: 10 Days  
Max 24 hrs: 14.6 mm 27th
Days without any rain: 20  
     
Air Frost: 0 Days  
Ground Frost: 0 Days  
Snow Falling: 0 Days  
Snow (50%) @ 9am: 0 Days  
Thunder Heard: 0 Days  
Hail <5 mm: 0 Days  
Hail >5 mm: 0 Days  
Fog @ 9am: 0 Days  
     
Total Monthly Sunshine: 202h:37m  
Total Monthly Sunshine: 202.6 Hours  
Most Sunshine in a Day: 15h:43m 30th
Average Daily Sunshine: 06h:32m  
Sunless Days: 1 Days  
Cloudless Days: 5 Days  
Total Possible Sunshine: 481h:38m  
Percentage of Total Sun: 42%  
     
Mean Soil Temp @ 30 cm: 13.1ºC  
Min Soil Temp @ 30 cm: 11.7ºC 1st
Max Soil Temp @ 30 cm: 17.0ºC 30th
Mean Soil Temp @ 100 cm: 11.4ºC  
Min Soil Temp @ 100 cm: 10.5ºC 1st
Max Soil Temp @ 100 cm: 12.8ºC 30th
     
Mean 10 Min Wind >39 mph: 0.0 Days  
N: 1.01 Days  
NE: 4.26 Days  
E: 2.38 Days  
SE: 4.23 Days  
S: 5.73 Days  
SW: 2.73 Days  
W: 7.74 Days  
NW: 1.29 Days  
Calm: 1.64 Days  
Mean Wind: 4.6 mph  
Max Gust: 32 mph 11th
     
Mean Cloud Cover: 60%  
Mean RH @ 9am: 83%  
Rain Duration >0.1mm/hour: 15.5 Hours  
Frost Duration: 0.0 Hours  
Max Frost Duration in a Day: 0.0 Hours  
     
Mean Sea Temperature: 12.9ºC  
Normal for Month:    
Max Sea Temperature: 15.3ºC 31st
Min Sea Temperature: 11.3ºC 4th
     
Mean Pressure @ 9am: 1017.6 hPa (+1.8 hPa)
Mean Pressure: 1017.8 hPa (+2.0 hPa)
Max Pressure: 1032.2 hPa 28th
Min Pressure: 999.6 hPa 16th
     
Max Dewpoint: 14.4ºC 25th
Min Dewpoint: 0.0ºC 4th
Mean Dewpoint: 7.2ºC  
     
Max Humidity: 91% 1st
Min Humidity: 38% 30th
Mean Humidity: 71% (-6)

 

A warm and changeable month though the last few days were settled and very sunny.

 

Quite cloudy at times mid-month with some rain but overall drier than average. Not as warm as May 2008, but equal to May 2007 though this May was sunnier and much drier than both.
Rainfall was below average.
There were no air frosts (have yet to record one in May) and no grass frosts either.
The amazing daily sunshine rates at the end of the month helped raise the total for the month to more respectable levels.
Soil temperatures were generally around normal at the beginning of the month but then were above average.
Winds were quite variable throughout the month with no really dominant direction.
Rainfall duration for the whole month was only 15.5 hours and reflected the dry nature of this month.
Sea temperatures gradually rose throughout the month and ended up rather above normal.
Mean pressure was 2.0 hPa above normal which is surprising given the generally settled nature of this month.
Dewpoints were significantly low at times until the last week of the month.
The dry air through most of the month meant relative humidity ended up being well below normal.
Weather Data for Otter Valley, Devon.  May 2009  
  Temp (oC) Hum (RH%) Dewpoint (oC) Wind (mph) Rain Pressure (hPa) Grass Sun  
  Min Max Ave Min Max Ave Min Max Ave Max Ave Run mm Min Max Ave Min Hours Observations
1 4.6 17.2 10.9 56 91 74 2.3 9.4 5.9 17 2.5 60 0.0 1018 1025 1022 2.0 3.2 Sunny intervals all day
2 6.4 18.2 12.3 43 90 67 4.1 9.4 6.8 14 2.7 65 0.0 1025 1030 1028 7.8 11.4 Sunny intervals all day
3 8.4 16.3 12.4 46 87 67 1.9 6.4 4.2 20 4.5 109 1.4 1027 1030 1029 6.2 11.1 Sunny intervals all day
4 3.3 12.8 8.1 63 89 76 0.0 7.3 3.7 22 3.0 73 0.0 1026 1031 1028 0.4 1.2 Sunny ints am, cloudy pm
5 10.4 18.2 14.3 60 88 74 6.9 10.9 8.9 23 6.5 157 0.0 1022 1026 1024 9.8 4.8  
6 11.1 17.9 14.5 63 85 74 7.5 11.4 9.5 24 6.6 159 0.0 1018 1022 1020 7.1 1.7 Brief sunny intervals all day
7 10.2 14.5 12.4 66 88 77 5.9 9.4 7.7 18 3.6 86 0.6 1010 1018 1014 6.5 0.8 Brief sunny intervals all day
8 7.1 15.6 11.4 51 83 67 3.2 6.5 4.9 27 6.7 160 1.6 1008 1017 1012 5.7 8.1 Sunny intervals all day
9 5.2 15.4 10.3 55 88 72 2.0 7.6 4.8 15 2.4 58 0.0 1015 1018 1016 1.7 3.0 Sunny intervals all day
10 4.1 20.8 12.5 45 89 67 0.8 9.3 5.1 14 2.8 67 0.0 1016 1018 1017 0.7 10.1 Sunny intervals all day
11 9.4 18.9 14.2 44 66 55 2.6 7.9 5.3 32 8.7 209 0.0 1017 1019 1018 7.2 14.8 Sunny all day
12 6.2 19.3 12.8 44 74 59 1.0 7.4 4.2 32 8.8 212 0.0 1017 1020 1018 4.1 8.4 Sunny intervals all day
13 8.9 13.8 11.4 53 86 70 3.4 9.8 6.6 17 4.0 95 0.0 1011 1018 1014 8.2 0.2 Brief sunny intervals all day
14 10.5 15.0 12.8 76 86 81 7.6 11.4 9.5 8 1.3 31 1.2 1006 1011 1008 8.8 0.6 Brief sunny intervals all day
15 9.3 12.6 11.0 61 90 76 2.4 9.5 6.0 25 4.0 95 6.8 1001 1006 1004 4.9 1.2 Showers, fine evening
16 9.1 15.0 12.1 53 91 72 3.4 8.7 6.1 28 8.0 191 2.6 1000 1007 1003 5.9 5.6 Sun & light showers all day
17 7.1 15.1 11.1 66 90 78 3.4 9.3 6.4 31 7.9 191 8.2 1001 1007 1004 5.5 1.7 Sunshine & showers all day
18 9.4 15.7 12.6 61 87 74 6.3 8.8 7.6 25 6.8 163 3.0 1006 1014 1010 7.1 3.1 Sunshine & showers all day
19 8.9 15.8 12.4 61 91 76 6.4 9.7 8.1 25 6.1 146 7.8 1014 1018 1016 5.4 4.5 Showers am, sunny ints pm
20 7.4 16.9 12.2 63 91 77 5.0 10.1 7.6 19 4.1 99 0.0 1017 1020 1018 4.1 8.8 Sunny intervals all day
21 7.8 17.6 12.7 56 90 73 5.3 8.8 7.1 20 3.5 84 1.6 1015 1017 1016 5.2 6.6 Sunny intervals all day
22 5.4 18.3 11.9 57 90 74 2.6 9.3 6.0 17 2.7 65 0.0 1017 1018 1017 3.6 8.2 Sunny intervals all day
23 8.2 21.7 15.0 48 90 69 4.4 10.9 7.7 16 2.1 51 0.0 1016 1019 1017 4.3 10.3 Sunny intervals all day
24 5.2 23.8 14.5 47 90 69 1.9 12.7 7.3 13 1.6 39 0.0 1017 1020 1019 2.2 13.8 Sunny all day
25 8.7 23.6 16.2 55 87 71 5.3 14.4 9.9 13 1.6 39 0.0 1012 1020 1016 6.3 2.7 Cloudy am, sunny ints pm
26 10.3 17.2 13.8 48 86 67 4.5 9.5 7.0 28 9.4 226 0.0 1011 1023 1017 5.5 8.7 Sunny intervals all day
27 8.5 13.9 11.2 68 91 80 4.4 11.8 8.1 24 4.9 118 14.6 1020 1025 1022 5.9 0.0 Rain am, cloudy pm
28 12.1 19.8 16.0 70 91 81 10.0 14.1 12.1 18 4.0 96 0.0 1025 1032 1028 11.5 1.5 Cloudy am, sunny ints pm
29 10.7 23.3 17.0 56 91 74 8.3 14.2 11.3 25 4.6 110 0.0 1025 1032 1028 7.8 15.6 Sunny all day
30 11.3 23.7 17.5 38 75 57 5.7 10.7 8.2 19 4.6 110 0.0 1023 1025 1024 6.5 15.7 Sunny all day
31 11.2 25.9 18.6 44 78 61 5.6 14.0 9.8 17 3.5 85 0.0 1023 1025 1024 6.5 15.3 Sunny all day
8.3 17.9 13.1 55 87 71 4.5 10.0 7.2 21 4.6 3445 49.4 1015 1020 1018 5.6 202.58  

Graphs for May 2009
Figure 1. Temperature and Rainfall for May 2009.
Figure 2. Sunshine, air pressure and mean wind speed for May 2009.
Figure 3. Wind direction for May 2009.
Figure 4. Soil & sea surface temperature (SST) for Lyme Bay for May 2009.
Figure 5. Wind run, maximum gusts and mean pressure for May 2009.