Monthly Archives: December 2017

December & 2017 Sunshine

Down ‘ere near the south Devon coast, yesterday’s unbroken sunshine from dawn ’til dusk has pushed the annual total to 1745 hours, which is still rather below my estimated LTA.

To this date last year there had been 1876 hours of sunshine.

December’s sunshine total now at 81 hours, which is around the average for the last 12 years. So, given today’s sunny start, this month should end up a little above normal.

Annual rainfall total at 720 mm, so pretty much average.

One thing of note though, is the mean temperature for this year, it is currently at 12.0C making it a ‘warm’ year. Surprising given the rather uninspiring summer and early autumn.

December Sunshine

Another day of unbroken sunshine today from dawn until dusk brings the monthly sunshine total to 66.5 hours.

This makes this month already sunnier than December 2016 (a dull 65.0 hours) but the main difference is temperature. Last year’s December was much, much warmer (mean temperature of 8.3C) compared to this month’s mean temperature of a rather lowly 5.4C.

Though this doesn’t tell the whole story, as the days haven’t been that cold (helped by the sunshine), it is the plethora of nights under clear, calm conditions that have led to an unusually high amount of air and grass frosts.

My sunniest December was in 2014 with 104 hours (2006 – 2016) and the average is 81 hours.

Summary for Autumn 2017

Slightly warmer than average with below normal rainfall and sunshine.

Mean Max: 16.1ºC
Mean Min: 8.2ºC
Mean: 12.2ºC

High Max: 23.1ºC 04 Sep
Low Max: 6.0ºC 30 Nov
High Min: 16.6ºC 04 Sep
Low Min: -3.2ºC 29 Nov
Grass Min: -5.0ºC 29 Nov

Days >20°C 8 Days
Days >15°C 60 Days
Nights >10°C 38 Days
Nights <5°C 26 Days

Rain Total (gauge): 170.5 mm
Rain Days >0.2 mm: 46 Days
Rain Days >1.0 mm: 31 Days
Max 24 hrs: 21.1 mm 03 Sep
Days without any rain: 45

Air Frost: 6 Days
Grass Frost: 14 Days
Snow Falling: 0 Days
Thunder Heard: 1 Day
Hail <5 mm: 1 Day
Hail >5 mm: 0 Days
Fog @ 9am: 1 Day

Total Autumn Sunshine: 382.8 Hours
Most Sunshine in a Day: 12.2 Hours 01 Sep
Average Daily Sunshine: 4.2 Hours
Sunless Days: 9 Days
Cloudless Days: 8 Days
Total Possible Sunshine: 979 Hours
Percentage of Total Sun: 39%

Ave 10 Min Wind >39 mph: 0.0
Mean Wind: 3.5 mph
Max Gust: 44 mph 23 Nov
Mean Cloud Cover: 52%

Mean Pressure: 1016.8 hPa
Max Pressure: 1030.9 hPa 27 Oct
Min Pressure: 985.5 hPa 23 Nov

Max Dewpoint: 19.7ºC 04 Sep
Min Dewpoint: -3.9ºC 29 Nov
Mean Dewpoint: 9.8ºC

Max Humidity: 100% Several days
Min Humidity: 50% 1st Sep
Mean Humidity: 87%

Summary for November 2017

A benign, sunny and rather windless month with well-below average rainfall. This November had the lowest wind run miles of any month this year to date (2009 miles) but conversely, this month also had the windiest day this year with 370 miles on the 22nd.

Mild (especially by day) until the 25th, then much colder making this month’s mean temperature end up below my eLTA.

An unusually high amount of grass and air frosts with a sharp frost on the 29th that finished off the chilli plants.

Mean Max: 12.3ºC
Mean Min: 4.2ºC
Mean: 8.3ºC

High Max: 16.0ºC 2nd
Low Max: 6.1ºC 30th
High Min: 13.4ºC 22nd
Low Min: -3.2ºC 29th
Grass Min: -5.0ºC 29th

Days >15°C 4 Days
Days >10°C 25 Days
Nights >10°C 3 Days
Nights <5°C 17 Days

Rain Total (gauge): 44.2 mm
Rain Days >0.2 mm: 13 Days
Rain Days >1.0 mm: 8 Days
Max 24 hrs: 7.9 mm 7th
Days without any rain: 17

Air Frost: 6 Days
Grass Frost: 13 Days
Snow Falling: 0 Days
Thunder Heard: 0 Days
Hail <5 mm: 0 Days
Hail >5 mm: 0 Days
Fog @ 9am: 0 Days

Total Monthly Sunshine: 128.1 Hours
Most Sunshine in a Day: 8.7 Hours 8th
Average Daily Sunshine: 4.3 Hours
Sunless Days: 2 Days
Cloudless Days: 5 Days
Total Possible Sunshine: 269.2 Hours
Percentage of Total Sun: 48%
Average Sunny Interval: 18.8 mins

Ave 10 Min Wind >39 mph: 0.00 Days
Calm: 8.14 Days 29%
Mean Wind: 2.8 mph
Max Gust: 44 mph 23rd
Mean Cloud Cover: 54%
Mean RH @ 9am: 96%

Mean Pressure: 1017.6 hPa
Max Pressure: 1030.5 hPa 17th
Min Pressure: 985.5 hPa 23rd

Max Dewpoint: 13.7ºC 4th
Min Dewpoint: -3.9ºC 29th
Mean Dewpoint: 6.0ºC

Max Humidity: 100% Several days
Min Humidity: 57% 17th
Mean Humidity: 87%

More details on the Otter Valley Weather website