Tonbridge-Weather.org.uk

DECEMBER 2010 daily and monthly summary

Return to Daily Summaries Index
Back to November
DECEMBER 2010
January 2011

1st - 3rd
Note: rainfall measurement this period approximate based on snow level. 1st (Wednesday), HP 1034 hPa Southern Norway, LP 993 hPa Adriatic, "snow train" from NE of intermittent light/moderate snow during the night giving 6cm snow first thing, continues to add another 4cm until late pm, after a brief pause further snow this time from LP over N France snow band from SE moving westwards - heavy for 90 mins or so evening and night adds another 5cm+. 2nd, continuing snow overnight deposits a covering of 22cm or so, light snows lasts all day and into the night making 72 hours of near continual snowfall. 3rd, LP 1005 hPa central France, LP 1003 hPa S Sweden, snowfall finally stopped sometime overnight am, fine start becoming misty, thin cloud all day but fairly bright, freezing fog becoming dense evening, -9.5 °C logged at 21:30 is lowest December temperature in site records and lowest since 1991 overall.
4th - 12th
4th (Saturday), LP 995 hPa NE Scotland, LP 975 hPa Azores, HP 1026 hPa Spain; dramatic temperature rise from -6.3 °C at 00:50 to +0.4 °C at 01.10, slow thaw morning reducing snow depth to around 13cm at 09.00, rain afternoon and late evening. 5th, mainly cloudy with sunny spell pm. 6th, rather dull day with mist. 7th, LP 994 hPa between Shetland/Norway, LP 988 hPa W of Portugal, HP 1030 hPa Mid Atlantic, bright day with sunshine pm. 8th, mainly cloudy with brief sunny intervals pm. 9th, another bright day with sunny spells from 10.00 to 15.00, still many patches of old snow/ice on pavements and gardens. 10th, cloudy day and mostly a little dull, slow thaw continues. 11th, cloudy with a little brightness. 12th, HP 1029 hPa N Scotland, sunny am, cloudy pm
13th - 16th
13th, mainly cloudy and misty with just a couple of brighter interludes. 14th, cloudy start with sunny spells later. 15th, HP 1046 hPa W of Ireland, LP 986 hPa Arctic Ocean about 77°N, sunny start, cloudy later with drizzle /light rain pm. 16th, cold front of polar origin tracks S across the UK preceded by rain am and pm, turning to sleet then two hours of snow by evening but not settling.
17th - 23rd
17th, Mid Atlantic HP 1033hPa, Lp 988 hPa E of Iceland, further LPs to NE of UK, trough moving SE brings 2 hours heavy snow during middle of day, settling quickly to a depth of 3cm. 18th, LP 989 hPa S England, occlusion brings snow from 08.00 - light and intermittent at first with one hour heavy snow ending just after midday, adding 5cm accumulation for a total of 8cm. 19th, a cloudy day with just a little brightness, very slight thaw, snow depth at 7cm. 20th, sunny spells with slight thaw followed by another band of snow as occlusions move in from SW giving 6 hours of new snow from 17.15, snow cover back up to 10cm. 21st, a murky day with fog late pm, slow thaw resumes. 22nd, snow cover down to 6.5cm, another cloudy day with mist and slow thaw. 23rd still mainly overcast, some very light sleety flurries pm and night, slow thaw continues with snow cover down to 3cm.
24th - 31st
24th, HP 1028 hPa Ireland, LP 992 hPa Gulf of Genoa, bright day with sunny spells, snow cover patchy at 1.5cm. 25th, bright day with some sunshine, no falling snow but patchy snow/ice still on the ground. 26th, sunny am, more hazy pm, still patchy snow/ice cover. 27th, cloudy and still the snow/ice remnants remain at < 1cm, light rain before midnight continuing into early am of 28th, thaw almost 100%, increasingly foggy during daytime and evening. 29th, LP 1004 hPa NW of Ireland, LP 993 hPa W of Portugal, HP over Scandinavia/E Europe/Spain, another foggy day with visibility 300m or less all day. 30th, foggy morning brightening up a little around lunchtime but remaining cloudy all day. 31st, overcast again and rather dull.

DECEMBER 2010 MONTHLY SUMMARY
ACTUAL TEMPERATURE
 AVERAGE
 Daily Maximum 2.7  ºC ( -4.9C )*
 Daily Minimum -1.1  ºC ( -4.6C )*
 Daily Mean
0.92
 ºC (c. -4.6C)
 EXTREMES
 High Maximum 7.3  ºC ( 11th  )
 Low Minimum -9.5  ºC (  3rd )
 Low Maximum -3.6  ºC (  3rd )
 High Minimum 4.6  ºC ( 11 & 30th  )
 
   
 Days with max => 10 °C 0   ( -9 )*
 Days with max <0 °C (ice days) 6   ( +6 )*
 Days with air frost 19   ( +12 )*
 
PRECIPITATION
 Monthly Total 34.7  mm ( 48% )*
 Days with measurable precip 15  Days ( -1 )*
   ...of which, days with >= 1.0 mm 9  Days ( -5 )*
   ...and days with snowfall observed 7  Days  
 Days with Snow Cover 20  Days  
 Greatest level snow depth 23  cm ( 2nd )
 RAIN RATE & EXTREMES
 High Rain Rate 6.0  mm/hr ( 4th )
 High Rain Total in 1 day 7.1  mm ( 2nd - snow )
 High Rain Total in 1 hour 2.8  mm ( 4th, 19.45h)
 EVAPO-TRANSPIRATION
 Total for month 7.3  mm  
 High Total for 1 day 0.7  mm ( 23rd  )
APPARENT TEMPERATURE
 Low Wind Chill -9.5  ºC (   3rd )
 DAVIS HEAT INDICES THW & THSW
 Low Temp/Hum/Wind Index -9.6  ºC (   3rd )
 High Temp/Hum/Wind Index 7.2  ºC ( 11th )
 High Temp/Hum/Sun/Wind Index 8.8  ºC ( 11th )
 
DEWPOINT & HUMIDITY
 High Dewpoint 6.1  ºC ( 30th )
 Low Dewpoint -11.4  ºC (  3rd )
 Average Dewpoint at 14h 0.0  ºC  
 Low Relative Humidity 59  % ( 14th )
 Average RH at 14h 85  %  
WIND SPEED & DIRECTION
 Monthly Average 1.0  mph  
 Windiest day (Average) 4.7  mph ( 23rd )
 Highest Gust 22  mph ( 24th )
 Dominant Direction N  ( 31% )
 
BAROMETER
 Monthly Mean 1012.9  hPa  
 High Barometer 1035.7  hPa ( 15th  )
 Low Barometer 988.0  hPa ( 18th )
SUNSHINE
 Max Sensor Exposure to direct sun
2.0
 hours/day (8 possible)
 Calculated Monthly Sunshine Hours
13.2
 hours  
 Estimated Actual Hours (approx)
30.0
 hours  
 Sunniest Day Measured
2.0
 hours ( 26th )
 Days with no sunshine
15
 Days  
 
FOG
 Number of Days with Fog 8  Days  
NEW SITE RECORDS SET THIS MONTH
  • Coldest December in site records.
  • Snowiest December in site records
  • Lowest minimum temperature for any December, -9.5 °C on the 3rd.
  • Lowest maximum temperature for any December, 7.3 °C on the 11th.
‡ SUN: Sunshine hours are calculated approximately and solely from solar radiation readings, but note that the solar sensor's exposure to sunshine is limited. The sensor receives only up to 25% of total possible sunshine exposure this month due to obstruction. There is no allowance for sunshine by visual observation only, so the sunniest day figures above can be very significantly less than the actual daily sunshine duration.
THW = Shaded Heat Index calculated with cooling/warming effect of wind and humidity to give an apparent temperature.
THSW = Unshaded Heat Index calculated with cooling/warming effect of wind, humidity and full direct sunshine to give an apparent temperature.
EVAPO-TRANSPIRATION is drying effect due to sun and wind, and is equivalent to "negative rainfall"

   DAILY STATS DECEMBER 2010
 
TEMPERATURE ºc
HUMIDITY
SUN ‡
PRESSURE
RAINFALL
WIND SPEED
DIRECTION
 WEATHER
 NOTES
DATE
Low
(21-09h)
High
(09-21h)
Temp at 14.00z
RH %
at 14.00z
Dewpoint ºc
at 14.00z
Bright
sun hrs
hPa   †
at 14.00z
Day Total
(mm)
Average
(mph)
Max Gust
(mph)
Dominant
(Compass)
 Precipitation
 type etc ‡
                       
1st
-1.6 -0.6 -1.2 88 -3.0 0.0 1003.0 FS 7.1 0.7 13 N  Snow
2nd
-3.9 -1.6 -2.3 88 -4.0 0.0 1005.6 ST 2.5 0.1 7 N  Snow
3rd
-5.1 -3.6 -3.8 89 -5.4 0.0 1011.0 FS 0.0 0.4 7 N  Cloud, freezing fog
4th
-9.5 5.4 5.1 92 3.9 0.0 1003.2 FS 6.6 1.4 18 SW  Rain
5th
0.8 2.1 1.9 91 0.6 0.5 1002.4 FS 0.3 0.4 6 SSW  Cloudy
6th
-2.7 -0.7 -1.2 92 -2.3 0.0 1000.2 FS 0.0 0.4 6 N  Mist
7th
-2.6 1.5 1.4 92 0.2 1.7 1002.6 FS 0.0 0.2 6 N  Sunny pm
8th
-0.4 1.7 1.7 86 -0.4 0.2 1010.7 R 0.0 2.7 18 N  Cloudy
9th
-2.3 3.8 3.7 71 -1.1 1.2 1029.2 ST 0.0 1.5 10 WNW  Sunny spells
10th
1.8 5.8 5.5 81 2.5 0.0 1030.0 FS 0.0 1.4 11 SSW  Cloudy
11th
4.6 7.3 7.2 79 3.8 0.5 1023.6 F 0.0 0.9 12 SSW  Cloudy
12th
1.2 5.5 5.3 79 2.0 0.3 1022.7 ST 0.0 0.8 10 N  Sunny am
13th
-0.7 2.9 1.1 92 -0.1 0.2 1026.1 FS 0.3 0.6 11 N  Cloudy, mist
14th
0.8 4.7 4.2 61 -2.6 1.5 1032.1 RS 0.0 1.0 10 N  Sunny spells
15th
-1.1 4.3 2.6 90 1.1 0.1 1032.1 F 1.0 1.1 12 SSW  Rain pm
16th
2.8 6.6 6.3 87 4.3 0.0 1000.5 FR 2.8 2.9 17 SW  Rain pm, snow eve
17th
-3.6 -0.9 -2.4 87 -4.3 0.2 995.5 FS 1.5 0.9 12 SW  Snow am/pm
18th
-8.6 0.9 0.9 91 -0.4 0.1 988.0 FS 4.1 0.5 12 WNW  Snow am
19th
-2.4 0.8 0.7 86 -1.4 0.2 989.0 FS 0.0 0.7 14 N  Cloudy
20th
-7.7 0.3 -0.8 86 -2.9 1.8 1000.6 FS 3.6 0.0 5 NW  Snow eve
21st
-0.6 2.1 2.0 92 0.8 0.0 1001.2 ST 0.3 0.0 3 NNW  Fog
22nd
0.0 1.7 1.7 93 0.7 0.0 1003.3 FS 0.0 1.0 16 N  Overcast
23rd
-0.2 2.2 2.1 80 -1.0 0.0 1006.8 ST 0.0 4.7 21 N  Cloudy
24th
0.0 2.3 2.1 71 -2.7 1.5 1016.6 RS 0.0 3.8 22 N  Sunny spells
25th
-1.8 -0.2 -0.2 85 -2.4 1.2 1027.2 RS 0.0 0.7 8 N  Sunny intervals
26th
-3.7 2.0 2.0 65 -3.9 2.0 1025.5 F 0.0 0.2 6 SW  Sunny periods
27th
-1.6 3.6 3.3 74 -0.9 0.0 1014.8 F 0.5 1.9 18 SE  Rain night pm
28th
2.2 4.1 3.8 92 2.7 0.0 1013.2 ST 2.0 0.0 7 SE  Rain night am
29th
3.8 6.8 6.8 94 5.9 0.0 1018.3 FS 0.3 0.0 2 ESE  Fog
30th
4.6 6.9 6.7 95 5.9 0.0 1023.0 FS 0.3 0.1 7 ENE  Fog am
31st
3.3 5.2 4.7 92 3.5 0.0 1024.8 FS 0.0 0.0 3 SE  Overcast
                         
‡ SUN: Sunshine hours are calculated approximately and solely from solar radiation readings, but note that the solar sensor's exposure to sunshine is rather limited. The sensor receives less than 25% of total possible sunshine exposure this month due to building obstruction, and there is no allowance for sunshine by visual observation only, so the figures above can be very significantly less than the actual daily sunshine duration.
† Barometer trend (previous 3 hours) : F = falling, ST = steady, R = rising; Q = quickly, S = slowly
Weather Notes: Predominant weather / type of precipitation.