December 2020 was colder than usual and was much wetter than average too. The average maximum temperature of 7.5°C was 0.9°C below the Usk average for December of 8.4°C. The maximum temperature exceeded 10°C on 7 days and there were 6 days of air frost too with the month ending with a cold spell.
There were 9 days when no significant rain was recorded (<0.2 mm). But these were accompanied by some very wet days (7 days with more than 10 mm) and the total rainfall was 257.4 mm, was 111% above the Usk* average for December of 121.9 mm.
This made it the wettest month since February 2014 (266.9 mm) and only the fourth time since April 2011 that 250 mm has been exceeded, the record being January 2014 (302.1 mm).
The 23rd was the wettest day with 54.8 mm, the third highest daily total since records started in April 2011 and only the fifth occasion on which 50 mm (just under 2 inches) has been recorded.
* Usk is the nearest Met Office station for which long term averages (1981-2010) are available.
Day by day data for December are given below:-
MONTHLY CLIMATOLOGICAL SUMMARY for DEC. 2020
NAME: Penallt210 CITY: Penallt STATE:
ELEV: 210 m LAT: 51° 48' 00" N LONG: 2° 42' 00" W
TEMPERATURE (°C), RAIN (mm), WIND SPEED (km/hr)
HEAT COOL AVG
MEAN DEG DEG WIND DOM
DAY TEMP HIGH TIME LOW TIME DAYS DAYS RAIN SPEED HIGH TIME DIR
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1 5.1 7.1 14:00 2.9 8:00 13.2 0.0 0.0 0.0 12.9 5:00 NE
2 5.2 8.2 13:30 2.9 19:00 13.1 0.0 0.2 0.0 9.7 15:30 WSW
3 4.0 5.3 14:00 1.9 20:30 14.3 0.0 11.0 0.0 12.9 9:00 SE
4 3.5 5.7 12:30 2.2 4:00 14.8 0.0 7.6 0.0 17.7 6:00 SW
5 3.4 5.7 13:30 0.7 8:00 14.9 0.0 5.6 1.8 24.1 12:30 NE
6 3.7 5.1 13:00 1.6 6:00 14.6 0.0 1.0 0.0 12.9 4:30 NE
7 2.3 3.9 0:30 -0.1 17:00 16.0 0.0 0.2 0.0 3.2 10:00 NE
8 3.9 6.2 14:00 1.6 3:00 14.4 0.0 0.2 0.0 3.2 17:00 ESE
9 4.2 6.0 23:30 1.2 8:00 14.1 0.0 3.8 1.3 24.1 23:00 SSE
10 6.8 7.9 00:00 5.9 0:30 11.5 0.0 5.6 2.9 20.9 2:00 SSE
11 8.1 9.8 13:30 5.6 22:00 10.2 0.0 0.4 0.0 11.3 1:00 SE
12 5.7 8.1 13:30 0.5 22:30 12.7 0.0 0.2 0.0 14.5 12:30 E
13 7.7 11.7 16:30 1.8 0:30 10.6 0.0 21.6 2.9 30.6 10:30 SSE
14 8.4 10.2 0:30 6.2 23:00 9.9 0.0 3.6 1.1 22.5 0:30 SE
15 7.2 9.5 12:30 6.1 5:00 11.1 0.0 0.6 0.5 19.3 14:30 SE
16 7.6 9.1 4:00 5.3 23:00 10.7 0.0 24.4 2.6 30.6 8:00 SSE
17 8.1 10.7 00:00 5.1 0:30 10.2 0.0 6.2 1.3 30.6 21:00 SE
18 11.4 12.0 12:30 10.6 0:30 6.9 0.0 30.0 4.2 37.0 21:00 SSW
19 8.4 10.9 1:30 5.8 23:30 9.8 0.0 16.8 0.6 27.4 1:00 SE
20 5.7 7.9 12:30 4.6 18:00 12.6 0.0 10.8 0.0 16.1 1:00 SE
21 10.2 12.4 14:00 5.8 0:30 8.1 0.0 16.0 0.6 20.9 7:30 SW
22 7.4 11.6 0:30 5.2 9:30 10.9 0.0 3.4 0.0 12.9 0:30 WSW
23 7.9 10.3 11:00 3.7 21:30 10.4 0.0 54.8 2.6 30.6 23:00 NE
24 2.8 5.3 2:30 0.3 23:30 15.5 0.0 0.0 0.6 25.7 0:30 NE
25 1.6 3.8 15:30 -0.4 3:30 16.7 0.0 0.0 0.0 1.6 1:00 SW
26 7.6 9.2 13:00 3.0 0:30 10.7 0.0 10.6 0.6 32.2 21:30 WSW
27 4.0 7.9 0:30 1.1 23:00 14.3 0.0 14.2 0.2 22.5 0:30 E
28 0.6 1.9 4:30 -1.3 00:00 17.7 0.0 4.8 0.0 19.3 15:00 NE
29 1.1 3.6 11:30 -1.7 1:30 17.2 0.0 3.6 0.0 12.9 16:00 NE
30 1.1 3.6 11:30 -1.2 21:30 17.3 0.0 0.0 0.0 3.2 2:30 SSE
31 -0.7 2.8 13:00 -2.8 00:00 19.0 0.0 0.2 0.0 1.6 3:30 SE
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5.3 12.4 21 -2.8 31 403.4 0.0 257.4 0.8 37.0 18 SE
Max >= 32.0: 0
Max <= 0.0: 0
Min <= 0.0: 6
Min <= -18.0: 0
Max Rain: 54.79 ON 23/12/20
Days of Rain: 27 (> .2 mm) 19 (> 2 mm) 4 (> 20 mm)
Heat Base: 18.3 Cool Base: 18.3 Method: Integration