Autumn 2008


A HDR image of a Dartmoor stream taken on a warm and humid September afternoon.

 

Summary for  Autumn 2008
Mean Max: 14.5ºC  
Mean Min: 7.6ºC  
Mean: 11.0ºC  
     
High Max: 21.3ºC 19th Sep
Low Max: 3.3ºC 29th Nov
High Min: 13.6ºC 9th Sep
Low Min: -1.9ºC 29th Nov
Mean Grass Min: 5.2ºC  
Grass Min: -4.0ºC 29th Nov
     
Rain Total (gauge): 286.2 mm  
Rain Total (tipping bucket): 374.9 mm  
Rain Days >0.2 mm: 48 Days  
Rain Days >1.0 mm: 32 Days  
Max 24 hrs: 70.8 mm 30th Oct
Days without any rain: 43  
     
Air Frost: 4 Days  
Ground Frost: 8 Days  
Snow Falling: 0 Days  
Snow (50%) @ 9am: 0 Days  
Thunder Heard: 3 Days  
Hail <5 mm: 1 Days  
Hail >5 mm: 0 Days  
Fog @ 9am: 2 Days  
     
Total Monthly Sunshine: 361h:52m  
Total Monthly Sunshine: 361.9 Hours  
Most Sunshine in a Day: 11h:34m 20th Sep
Average Daily Sunshine: 03h:58m  
Sunless Days: 13 Days  
Cloudless Days: 9 Days  
Total Possible Sunshine: 977h:19m  
Percentage of Total Sun: 37%  
     
Mean Soil Temp @ 30 cm: 11.0ºC  
Min Soil Temp @ 30 cm: 4.8ºC 30th Nov
Max Soil Temp @ 30 cm: 15.2ºC 7th Sep
Mean Soil Temp @ 100 cm: 11.8ºC  
Min Soil Temp @ 100 cm: 7.4ºC 30th Nov
Max Soil Temp @ 100 cm: 15.2ºC 1st Sep
     
Mean 10 Min Wind >39 mph: 0.5 Days  
N: 12.04 Days  
NE: 6.17 Days  
E: 4.40 Days  
SE: 7.34 Days  
S: 14.82 Days  
SW: 11.56 Days  
W: 16.96 Days  
NW: 9.08 Days  
Calm: 8.63 Days  
Mean Wind: 4 mph  
Max Gust: 41 mph 7th Oct
     
Mean Cloud Cover: 62%  
Rain Duration >0.1mm/hour: 136.8 Hours  
Frost Duration: 21.0 Hours  
Max Frost Duration in a Day: 7.5 Hours 29th Nov
     
Mean Sea Temperature: 14.3ºC  
Normal for Month:    
Max Sea Temperature: 17.3ºC 13th Sep
Min Sea Temperature: 10.2ºC 30th Nov
     
Mean Pressure: 1015.2 hPa  
Max Pressure: 1034.7 hPa 26th Sep
Min Pressure: 983.2 hPa 5th Sep
     
Max Dewpoint: 16.8ºC 6th Sep
Min Dewpoint: -4.2ºC 29th Nov
Mean Dewpoint: 7.1ºC  
     
Max Humidity: 94% 7th Oct
Min Humidity: 47% 20th Sep
Mean Humidity: 79%  

This autumn was in contrast to last year's autumn which was predominantly settled, sunny and warm. Apart from the occasional settled few days this autumn was generally wet and with no prolonged dry, calm weather. In other words, this autumn carried on where the summer ended. There was a notable cold snap at the end of October which brought the earliest air frost (29th Oct) recorded at this station.

Unusually for September, there were no really warm or hot days, this was a continuation of the 'summer without heat' weather-theme. Contrastingly, October and November had a few warm and sunny 'summer-like' days.

Overall it was a wet autumn with no dry periods of any significant length.
A relatively thunderless, hailless and foggyless autumn.
Sunshine levels were below last year's autumn and a reflection of the unsettled nature of these 3 months.
Soil temperatures were variable due to the high rainfall.
Westerly or north-westerly winds were dominant for much of the autumn with only brief anticyclonic spells. It was also quite windy at times (though not unusually so) especially during the first week of September & October.
The less-than-average sunshine for this autumn is shown by the high amount of cloud cover (62%).
Sea temperatures remained around average for much of the autumn but ended up slightly below during the latter part of October.
Mean pressure was below normal and indicative of the generally unsettled nature of this autumn.
Dewpoints were quite high during a humid spell in early September but fell away during brief incursions of Arctic air at the end of October and the last week of November.
Relative humidity was around normal.
Graphs for Autumn 2008
 

Figure 1. Temperature and Rainfall for Autumn 2008.
Figure 2. Sunshine, air pressure and mean wind speed for Autumn 2008.
Figure 3. Wind direction for Autumn 2008.
Figure 4. Sea Surface Temperature (SST) for Lyme Bay for Autumn 2008.
Figure 5. Wind run, gusts and air pressure for Autumn 2008.