April 2012

Spectacular Triassic sandstone cliffs and sea stacks at the western end of Jacob's Ladder Beach, Sidmouth on a warm and sunny March day.
Thurlestone Rock, South Devon.
Summary for  April 2012
Mean Max: 12.7ºC (-0.0ºC)
Mean Min: 3.5ºC (-0.9ºC)
Mean: 8.1ºC (-0.4ºC)
     
High Max: 15.9ºC 8th
Low Max: 8.0ºC 4th
High Min: 9.7ºC 9th
Low Min: -1.5ºC 16th
Mean Grass Min: 2.2ºC  
Grass Min: -2.4ºC 6th
     
Rain Total (gauge): 128.0 mm (285%)
Rain Total (tipping bucket): 127.2 mm (283%)
Rain Days >0.2 mm: 18 Days  
Rain Days >1.0 mm: 16 Days  
Max 24 hrs: 26.0 mm 25th
Days without any rain: 12  
     
Air Frost: 3 Days  
Ground Frost: 8 Days  
Snow Falling: 0 Days  
Snow (50%) @ 9am: 0 Days  
Thunder Heard: 2 Days  
Hail <5 mm: 4 Days  
Hail >5 mm: 0 Days  
Fog @ 9am: 0 Days  
     
Total Monthly Sunshine: 146.8 Hours (76%)
Most Sunshine in a Day: 12.3 Hours 1st
Average Daily Sunshine: 4.9 Hours  
Sunless Days: 3 Days  
Cloudless Days: 2 Days  
Total Possible Sunshine: 415.9 Hours  
Percentage of Total Sun: 35%  
Maximum UV Index: 5.7 24th
Time of Max UV   13:45
     
Mean Soil Temp @ 30 cm: N/A  
Min Soil Temp @ 30 cm: N/A  
Max Soil Temp @ 30 cm: N/A  
Mean Soil Temp @ 100 cm: N/A  
Min Soil Temp @ 100 cm: N/A  
Max Soil Temp @ 100 cm: N/A  
     
Mean 10 Min Wind >39 mph: 0.00 Days  
N: 9.81 Days  
NE: 1.62 Days  
E: 1.71 Days  
SE: 2.06 Days  
S: 4.77 Days  
SW: 2.92 Days  
W: 0.98 Days  
NW: 5.54 Days  
Calm: 0.59 Days  
Wind Chill Low: -3.1ºC 16th
Mean Wind: 4.1 mph  
Max Gust: 38 mph 30th
  30.00 Days  
Mean Cloud Cover: 65%  
Mean RH @ 9am: 92%  
Rain Duration >0.1mm/hour: 73.0 Hours  
Frost Duration: 18.0 Hours  
Max Frost Duration in a Day: 7.3 Hours 16th
     
Mean Sea Temperature: 10.3ºC (-0.1ºC)
Normal for Month: 10.4ºC  
Max Sea Temperature: 11.7ºC 27th
Min Sea Temperature: 9.8ºC 19th
     
Mean Pressure @ 9am: 1003.6 hPa (-12.6 hPa)
Mean Pressure: 1004.0 hPa (-12.2 hPa)
Max Pressure: 1027.0 hPa 16th
Min Pressure: 974.5 hPa 25th
   
Radiation Daily Mean 13.07 MJ/m²  
Max Daily Value 22.64 MJ/m² 15th
Min Daily Value 3.00 MJ/m² 29th
Number of Days with Data 30 Days  
1-Hour Maximum 1097 W/m² 27th
Starting Time of the Hour   12:00
     
Max Dewpoint: 11.4ºC 27th
Min Dewpoint: -3.1ºC 16th
Mean Dewpoint: 4.9ºC  
     
Max Humidity: 98% 2nd 
Min Humidity: 40% 15th
Mean Humidity: 80% (+2)

 

A cool, wet month.

This April has broken a trend towards ever drier and warmer Aprils that started in 2007.

There were no warm days (temperature >16.0°C), but no really cold ones either with the last air frost occurring on the 16th.
Rainfall was well above the average, with this month ending up the wettest April since before 2005. There were two particularly wet days on the 26th and the 29th.
There were 3 air frosts, all of which were slight, and there were 8 ground frosts. As usual for April, no snow was seen falling. A very showery month with two thunderstorms and hail falling on 4 days.
As can be expected from it being a very wet month, sunshine levels were rather below average and there were only two days of unbroken sunshine.
No soil temperature readings were taken due to relocation of sensors.
The dominant wind direction was northerly though southerly winds also dominated, due to frequent sea breezes. On the whole this was a breezy month. A maximum gust of 38 mph on the 30th is rather high for April, especially so late in the month, and caused trees to be damaged as they were in full leaf by then.
Rainfall duration of 73 hours shows just how wet this month was, and with 65% cloud-cover, this was also a cloudy month.
Sea surface temperatures actually fell slowly through the month until the 19th, then started to rise.
Mean pressure was well below the average for April and indicative of the unsettled nature of this month.
A new sensor has been added that measures solar irradiance in watts per square metre falling on a horizontal surface.
Dewpoints were often below the average due to cold, dry northerly airstreams.
Despite the lower than average dewpoints, the relative humidity was slightly above normal.
Weather Data for Otter Valley, Devon.  April 2012  
  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 1.1 12.4 6.8 51 93 72 -1.1 6.2 2.6 14 2.4 58 0.0 1017 1023 1020 -0.9 12.3 Sunny all day
2 -1.3 14.8 6.8 51 98 75 -2.4 7.0 2.3 12 2.1 49 0.0 1007 1017 1012 -1.5 11.3 Sunny all day
3 0.3 14.1 7.2 56 98 77 -1.2 8.4 3.6 15 3.0 71 0.0 1003 1007 1005 -1.0 2.2 Sunny intervals all day
4 3.8 8.0 5.9 70 91 81 1.5 4.4 3.0 17 2.5 61 2.0 1003 1011 1007 1.7 1.6 Sunny ints, showers pm
5 5.3 10.2 7.8 74 92 83 3.5 6.8 5.2 17 3.5 85 0.0 1012 1019 1015 3.6 0.3 Cloudy am, sunny ints pm
6 -1.3 13.7 6.2 47 96 72 -2.7 5.4 1.4 14 2.6 63 0.0 1013 1020 1017 -2.4 7.9 Sunny am, cloudy pm
7 4.1 13.9 9.0 69 96 83 2.0 9.1 5.6 11 1.9 46 0.0 1011 1015 1013 3.4 0.1 Sunny ints am, cloudy pm
8 5.8 15.9 10.9 66 96 81 3.8 11.0 7.4 17 2.3 55 0.0 1011 1017 1014 6.6 1.6 Sunny intervals all day
9 9.7 11.7 10.7 78 95 87 6.6 10.0 8.3 26 6.3 152 3.8 987 1011 999 8.3 0.0 Rain, intermittent all day
10 2.7 12.6 7.7 56 97 77 1.3 9.4 5.4 16 3.5 85 3.2 987 994 990 0.4 8.8 Sunny am, showers pm
11 1.4 14.8 8.1 46 98 72 0.3 6.4 3.4 14 2.5 60 0.0 994 1001 998 0.5 11.1 Sunny ints am, sunny pm
12 1.3 14.6 8.0 52 98 75 0.0 7.8 3.9 14 2.3 56 0.0 1002 1005 1003 0.2 5.3 Sunny intervals all day
13 0.3 14.2 7.3 58 98 78 -1.1 7.6 3.3 16 2.5 61 0.0 1004 1006 1005 -0.4 11.8 Sunny intervals all day
14 1.3 10.8 6.1 68 98 83 0.2 6.9 3.6 12 1.9 45 0.4 1004 1011 1007 0.2 1.8 Sun and showers all day
15 1.7 12.8 7.3 40 91 66 -0.6 3.6 1.5 18 4.2 100 0.0 1011 1025 1018 0.4 10.0 Sunny intervals all day
16 -1.5 12.0 5.3 61 96 79 -3.1 5.6 1.3 20 3.7 90 1.6 1019 1027 1023 3.1 7.5 Sun and showers all day
17 6.2 12.6 9.4 60 96 78 3.4 9.0 6.2 36 8.8 211 9.6 995 1019 1007 2.8 5.9 Sun and showers all day
18 5.6 10.6 8.1 76 94 85 3.3 7.9 5.6 33 7.5 179 5.8 976 995 986 4.6 0.9 Sun and showers all day
19 7.1 11.4 9.3 68 88 78 4.7 7.4 6.1 21 5.6 134 0.0 982 992 987 4.6 5.1 Sunny intervals all day
20 1.5 13.4 7.5 63 98 81 0.3 7.0 3.7 19 2.0 51 3.0 992 996 994 -0.3 5.2 Sun and showers all day
21 0.6 13.6 7.1 54 98 76 -0.5 7.3 3.4 22 3.1 75 1.2 995 1004 999 -1.7 10.4 Sunny intervals all day
22 2.3 13.0 7.7 73 98 86 1.1 9.2 5.2 20 2.9 69 2.2 1003 1005 1004 1.3 4.8 Sun and showers all day
23 3.6 10.3 7.0 84 97 91 2.0 9.1 5.6 22 3.7 88 19.6 985 1004 995 2.3 0.1 Rain am, showers pm
24 3.1 14.6 8.9 58 98 78 2.1 8.1 5.1 17 2.9 64 8.8 994 1001 998 1.6 6.1 Sun and showers all day
25 7.1 12.1 9.6 79 97 88 5.5 9.9 7.7 32 8.5 201 26.0 975 998 986 6.6 1.8 Sunny ints am, then rain
26 5.1 13.0 9.1 73 98 86 4.1 9.4 6.8 26 8.1 194 1.4 978 1001 990 3.4 2.0 Sun and showers all day
27 7.0 15.2 11.1 72 97 85 5.2 11.4 8.3 21 3.9 94 0.4 1001 1012 1007 5.0 7.4 Sunny intervals all day
28 7.9 10.7 9.3 83 96 90 6.0 9.1 7.6 20 2.7 66 2.2 1012 1016 1014 7.7 0.0 Cloudy all day
29 5.3 10.1 7.7 79 97 88 3.6 9.5 6.6 33 8.1 195 24.6 995 1013 1004 4.9 0.0 Rain all day
30 8.1 14.3 11.2 71 94 83 6.7 10.1 8.4 38 8.2 196 11.4 997 1012 1005 7.8 3.5 Rain am, sunny ints pm
3.5 12.7 8.1 65 96 80 1.9 8.0 4.9 20 4.1 2954 127.2 999 1009 1004 2.4 146.8  

Graphs for April 2012
Figure 1. Temperature and Rainfall for April 2012.
Figure 2. Sunshine, UV Index and solar irradiance for April 2012.
Figure 3. Wind direction for April 2012.
Figure 4. Sea surface temperature & cooling/heating days for April 2012.
Figure 5. Mean wind speed, calm hours and air pressure for April 2012.