December 2017 weather data

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(Jan 2018: updated to compare with Usk and not Ross-on-Wye)

With its two significant periods of snow, December 2017 was colder yet had no more precipitation than usual overall. 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 8 days and there were 7 days of air frost too.

The coldest temperature was -3.6°C on the 12th (in Pentwyn, whereas it dropped to -8.9°C in Monmouth at the same time).

There were 11 days when no significant rain was recorded (<0.2 mm); the total rainfall was 121.4 mm, almost exactly the Usk* average for December of 121.9 mm.

20 cm of snow depth was recorded in Pentwyn on the 10th and a further 7 cm on the 27th.

* 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. 2017

NAME: Penallt 210 CITY: 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
------------------------------------------------------------------------------------
1 2.5 5.5 14:00 0.2 7:30 14.8 0.0 0.0 1.0 12.9 4:30 E
2 5.4 7.9 12:30 2.2 2:00 11.0 0.0 0.0 0.0 4.8 13:30 SW
3 7.3 10.3 12:30 4.5 23:30 11.1 0.0 0.0 0.0 9.7 14:00 SW
4 6.7 8.7 11:30 4.3 5:00 11.6 0.0 0.0 0.0 4.8 1:00 W
5 6.9 8.2 13:30 5.7 8:00 11.4 0.0 0.0 0.0 8.0 13:00 W
6 8.6 9.7 00:00 7.5 0:30 9.7 0.0 2.2 3.2 25.7 21:00 SE
7 7.6 11.6 8:00 2.0 00:00 10.7 0.0 8.8 2.7 24.1 3:30 W
8 0.9 2.5 1:00 -0.7 00:00 17.4 0.0 1.6 0.8 19.3 3:30 W
9 0.6 3.1 13:00 -1.4 5:30 17.8 0.0 0.0 0.0 6.4 1:00 W
10 0.0 0.9 1:00 -0.6 20:30 18.4 0.0 20.0 0.8 14.5 7:00 ENE
11 -0.7 0.5 12:30 -2.1 00:00 19.1 0.0 0.0 0.0 6.4 13:00 SW
12 0.9 5.4 00:00 -3.6 4:30 17.4 0.0 1.6 1.0 17.7 20:00 WSW
13 4.1 6.6 13:00 2.1 22:00 14.2 0.0 4.8 1.6 20.9 21:30 W
14 3.5 5.6 12:30 2.1 8:30 14.8 0.0 1.6 1.6 20.9 3:00 W
15 3.5 6.0 12:00 1.3 00:00 14.8 0.0 0.8 1.3 14.5 5:30 E
16 2.8 6.6 12:30 0.1 8:30 15.5 0.0 0.0 0.2 8.0 12:00 W
17 6.3 9.8 20:30 1.1 0:30 12.1 0.0 1.8 0.8 14.5 14:30 W
18 4.3 7.8 12:00 2.2 9:00 14.0 0.0 0.0 0.0 6.4 14:30 E
19 6.0 8.9 14:30 2.0 7:30 12.3 0.0 0.0 0.2 9.7 21:00 W
20 9.8 13.3 12:30 7.4 3:00 8.5 0.0 1.6 0.0 9.7 1:00 W
21 9.8 10.7 13:00 8.6 22:00 8.6 0.0 1.2 0.5 16.1 16:00 W
22 9.4 10.2 13:00 8.7 9:00 8.9 0.0 2.2 0.2 9.7 4:30 W
23 8.1 10.9 13:00 6.9 9:30 10.2 0.0 0.2 0.6 11.3 22:30 W
24 8.4 8.9 3:00 7.8 10:00 9.9 0.0 0.8 2.9 22.5 22:30 W
25 7.9 9.9 14:30 3.0 00:00 10.4 0.0 11.2 3.9 29.0 11:00 SE
26 3.3 5.1 13:00 0.3 00:00 15.1 0.0 17.6 1.8 22.5 21:30 ENE
27 0.9 3.0 12:30 -0.4 00:00 17.4 0.0 1.4 0.6 14.5 9:30 E
28 0.7 4.2 12:30 -1.1 21:00 17.6 0.0 6.2 0.0 8.0 00:00 W
29 4.2 6.6 11:30 1.1 0:30 14.2 0.0 21.4 2.4 25.7 13:00 W
30 9.4 11.6 12:30 4.1 0:30 8.9 0.0 2.2 3.7 22.5 5:00 W
31 7.9 11.7 2:30 4.4 00:00 10.4 0.0 12.2 3.1 25.7 1:30 W
-------------------------------------------------------------------------------------
5.1 13.3 20 -3.6 12 408.2 0.0 121.4 1.1 29.0 25 W

Max >= 32.0: 0
Max <= 0.0: 0
Min <= 0.0: 7
Min <= -18.0: 0
Max Rain: 21.41 ON 29/12/17
Days of Rain: 21 (> .2 mm) 11 (> 2 mm) 1 (> 20 mm)
Heat Base: 18.3 Cool Base: 18.3 Method: Integration