September 2011

The misty cliffs at Branscombe on a day with a warm and humid maritime tropical air.
The misty cliffs at Branscombe on a day with a warm and humid maritime tropical air stream.

Summary for  September 2011
Mean Max: 20.0C (+1.5C)
Mean Min: 12.5C (+2.6C)
Mean: 16.2C (+2.0C)
     
High Max: 27.2C 29th
Low Max: 15.2C 18th
High Min: 17.1C 9th
Low Min: 4.6C 15th
Mean Grass Min: 9.7C  
Grass Min: 3.9C 15th
     
Rain Total (gauge): 51.4 mm (145%)
Rain Total (tipping bucket): 49.4 mm (139%)
Rain Days >0.2 mm: 17 Days  
Rain Days >1.0 mm: 12 Days  
Max 24 hrs: 8.8 mm 18th
Days without any rain: 13  
     
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: 163h:59m  
Total Monthly Sunshine: 164.0 Hours (78%)
Most Sunshine in a Day: 12.6 1st
Average Daily Sunshine: 05h:28m  
Sunless Days: 1 Days  
Cloudless Days: 4 Days  
Total Possible Sunshine: 379h:07m  
Percentage of Total Sun: 43%  
Maximum UV Index: 6 5th
Average UV Index: 3.7  
     
Mean Soil Temp @ 30 cm: 16.7C  
Min Soil Temp @ 30 cm: 15.9C 20th
Max Soil Temp @ 30 cm: 17.7C 30th
Mean Soil Temp @ 100 cm: 17.4C  
Min Soil Temp @ 100 cm: 17.1C 22nd 
Max Soil Temp @ 100 cm: 17.6C 5th
     
Mean 10 Min Wind >39 mph: 0.00 Days  
N: 0.39 Days  
NE: 0.85 Days  
E: 2.60 Days  
SE: 5.45 Days  
S: 6.06 Days  
SW: 6.07 Days  
W: 5.54 Days  
NW: 1.47 Days  
Calm: 2.56 Days  
Wind Chill Low: 4.4C 15th
Mean Wind: 4.7 mph  
Max Gust: 31 mph 12th
     
Mean Cloud Cover: 60%  
Mean RH @ 9am: 88%  
Rain Duration >0.1mm/hour: 32.5 Hours  
Frost Duration: 0.0 Hours  
Max Frost Duration in a Day: 0.0 Hours 1st
     
Mean Sea Temperature: 17.0C (+0.1C)
Normal for Month: 16.9C  
Max Sea Temperature: 17.7C 30th
Min Sea Temperature: 16.4C 20th
     
Mean Pressure @ 9am: 1012.8 hPa (-5.2 hPa)
Mean Pressure: 1013.4 hPa (-4.6 hPa)
Max Pressure: 1027.7 hPa 27th
Min Pressure: 1000.0 hPa 12th
     
Max Dewpoint: 20.2C 29th
Min Dewpoint: 2.0C 15th
Mean Dewpoint: 11.4C  
     
Max Humidity: 93% 28th
Min Humidity: 51% 30th
Mean Humidity: 77% (-4)

 

A generally unsettled, and often quite cloudy month.

September started warm and sunny but things soon cooled a little as it became more unsettled. Temperatures recovered somewhat during the final week and the last few days of the month were very warm and sunny as high pressure became established.

Rainfall was above the average but there were no really wet days.
As would be expected for September, there were no air or grass frosts.
Sunshine levels were well below the long term average but a sunny end to the month helped boost this month's figures and the month ended just a little below the LTA for September.
Soil temperatures were around normal at the beginning of the month but due to the warm spell during the final week of the month, they recovered and ended up above normal.
Wind was dominant from the SW, S & SE directions. It was not a particularly windy month with the maximum gust recorded only 31 mph.
Rainfall duration was 32.5 hours, most of which was in the form of light and patchy rain.
Sea surface temperatures were slightly above normal at the beginning of the month and generally stayed that way.
Mean pressure was below the average for September and indicative of the unsettled nature of this month.
Dewpoints were a little below average. Note a high DP of 20.2C, this is the highest dewpoint recorded at this station since before 2005.
The RH ended up being below normal due to regular incursions of fairly dry, cool air.
Weather Data for Otter Valley, Devon.  September 2011  
  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 11.6 23.4 17.5 53 89 71 6.4 14.6 10.5 21 4.3 103 0.0 1010 1014 1012 7.9 12.6 Sunny all day
2 10.3 26.2 18.3 57 91 74 7.7 17.3 12.5 13 1.5 36 0.0 1010 1014 1012 9.6 9.3 Misty am, sunny pm
3 13.9 19.7 16.8 70 89 80 10.9 15.1 13.0 19 4.8 116 0.0 1005 1010 1008 11.7 1.3 Brief sunny intervals all day
4 12.9 19.7 16.3 52 90 71 8.5 13.9 11.2 21 4.5 107 3.4 1005 1007 1006 8.5 6.0 Sunny intervals all day
5 8.9 17.5 13.2 68 90 79 6.3 12.4 9.4 26 5.4 131 3.2 1007 1015 1011 7.6 5.4 Sunny intervals all day
6 14.6 18.1 16.4 69 91 80 9.4 14.9 12.2 27 8.8 210 5.9 1006 1015 1010 10.4 0.0 Cloudy all day
7 11.7 16.1 13.9 69 87 78 8.1 11.0 9.6 27 6.6 157 1.1 1008 1014 1011 9.5 2.5 Sun and showers all day
8 13.8 21.4 17.6 70 84 77 9.8 16.2 13.0 17 4.8 115 0.0 1008 1014 1011 12.3 1.5 Sunny intervals all day
9 17.1 19.9 18.5 82 91 87 13.4 16.7 15.1 16 4.1 97 0.4 1007 1011 1009 14.0 0.8 Sun ints am, drizzle pm
10 17.1 19.9 18.5 70 92 81 11.8 16.3 14.1 24 7.8 187 0.8 1001 1007 1004 13.9 3.1 Sun and showers all day
11 12.6 20.2 16.4 57 90 74 9.9 12.9 11.4 27 6.9 166 1.9 1001 1006 1003 10.7 6.8 Sunny intervals all day
12 15.7 19.1 17.4 58 91 75 9.2 15.7 12.5 31 10.2 245 0.8 1000 1010 1005 10.7 4.0 Sunny intervals all day
13 12.2 17.6 14.9 57 86 72 6.6 11.9 9.3 31 6.6 158 1.3 1010 1017 1014 8.1 8.3 Sunny intervals all day
14 10.4 18.4 14.4 56 91 74 6.5 12.2 9.4 16 4.4 105 3.6 1017 1020 1018 6.0 4.9 Sunny intervals all day
15 4.6 20.6 12.6 54 92 73 2.0 11.9 7.0 13 1.4 35 0.0 1017 1021 1019 3.9 11.8 Sunny all day
16 12.1 22.4 17.3 58 90 74 6.6 14.9 10.8 21 3.7 90 0.0 1010 1017 1013 10.3 5.1 Sunny intervals all day
17 13.6 16.6 15.1 59 87 73 7.5 10.8 9.2 24 5.9 143 7.1 1004 1011 1008 8.6 6.6 Suns and showers all day
18 9.3 15.2 12.3 77 92 85 6.2 11.5 8.9 29 6.4 155 8.8 1003 1009 1006 7.3 4.7 Sun and showers all day
19 11.2 16.2 13.7 82 92 87 5.8 13.3 9.6 14 2.5 61 1.7 1009 1017 1013 6.7 0.3 Sunny ints and showers
20 13.2 18.0 15.6 81 90 86 11.2 14.3 12.8 21 4.8 124 3.4 1016 1018 1017 12.9 0.4 Cloudy all day, rain evening
21 11.2 17.4 14.3 58 92 75 8.1 11.0 9.6 20 4.1 99 0.8 1017 1018 1017 9.7 6.3 Sunny intervals all day
22 13.1 19.1 16.1 56 86 71 6.7 11.3 9.0 20 4.2 101 0.0 1018 1021 1019 6.0 8.5 Sunny intervals all day
23 6.3 19.4 12.9 62 92 77 3.4 12.7 8.1 16 2.7 66 0.0 1014 1021 1018 5.4 7.7 Sunny intervals all day
24 11.3 18.8 15.1 67 92 80 8.5 13.3 10.9 16 3.1 68 0.0 1012 1014 1013 9.1 2.8 Sunny intervals all day
25 15.1 20.1 17.6 69 92 81 11.5 14.8 13.2 18 6.0 144 4.4 1012 1015 1013 12.9 5.0 Rain then sunny intervals
26 15.1 20.6 17.9 73 91 82 11.5 15.7 13.6 13 3.5 84 0.8 1014 1024 1019 11.4 4.1 Sunny intervals all day
27 13.2 18.6 15.9 81 92 87 10.5 15.0 12.8 13 2.1 51 0.0 1024 1028 1026 10.6 0.7 Cloudy am, sunny ints pm
28 14.8 24.9 19.9 60 93 77 11.8 16.8 14.3 17 3.9 94 0.0 1021 1027 1024 11.8 11.4 Sunny all day
29 13.2 27.2 20.2 55 93 74 10.3 20.2 15.3 14 2.5 59 0.0 1021 1022 1021 11.0 11.2 Sunny all day
30 15.2 26.2 20.7 51 91 71 11.8 16.4 14.1 13 3.2 75 0.0 1019 1021 1020 11.1 10.9 Sunny all day
12.5 20.0 16.2 64 90 77 8.6 14.2 11.4 20 4.7 3377 49.4 1011 1016 1013 9.7 164.0  

Graphs for September 2011

Figure 1. Temperature and Rainfall for September 2011.
Figure 2. Sunshine, air pressure and mean wind speed for September 2011.
Figure 3. Wind direction for September 2011.
Figure 4. Soil & sea surface temperature (SST) for Lyme Bay for September 2011.
Figure 5. Wind run, maximum gusts and mean pressure for September 2011.