Climate averages 1991–2020

Swansea weather
in December.

A cool, wet month: the 10th warmest and the wettest of the year.

Long-term climate patterns, not a forecast for a particular trip.

Average high 8.2°C Daytime mean, December

Average low 4.7°C Night-time mean, December

Rainfall 145 mm 17 days with ≥1 mm

Daylight 8 h Sunrise to sunset, per day

December is a cool month in Swansea: daytime highs average 8.2°C and nights cool to about 4.7°C. By daytime temperature it is the 10th warmest of the 12 months.

Expect about 145 mm of rain on roughly 17 days, which makes December a wet month (the wettest month of the year). Daylight, from sunrise to sunset, lasts about 7 h 55 min on an average December day.

The nearest other city in this atlas is Cardiff (55 km away). In December its highs average 7.9°C, about as warm as Swansea, with 107 mm of rain.

Among the 143 cities listed in the United Kingdom, Swansea ranks 13th of 143 for the warmest December highs and 143rd of 143 for the driest December (rainfall, lowest first). The mean December high of those 143 cities is 7.2°C; Swansea is 1.0°C warmer than that mean.

From December to January, average highs fall by 0.6°C to 7.7°C, and monthly rainfall falls from 145 mm to 128 mm.

The annual picture

December in context

30-year average

Average highAverage low°C

Monthly rainfall

Average total · mm

Averages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated

Every month, side by side

Swansea climate table

1991–2020

Monthly climate averages for Swansea, 1991–2020
Month	Average highHigh / low	Average low	Rainfall mm/month	Rain days ≥1 mm/day	Daylight hours/dayDaylight h/day
January	7.7°C4.0°C	4.0°C	128	17.0	8.48 h
February	7.8°C3.7°C	3.7°C	92	13.1	9.910 h
March	9.4°C4.5°C	4.5°C	83	13.7	11.812 h
April	11.8°C6.1°C	6.1°C	69	12.0	13.814 h
May	14.6°C8.8°C	8.8°C	72	12.4	15.616 h
June	16.9°C11.6°C	11.6°C	79	12.2	16.617 h
July	18.5°C13.5°C	13.5°C	86	13.8	16.216 h
August	18.5°C13.8°C	13.8°C	101	14.3	14.615 h
September	16.8°C12.1°C	12.1°C	96	13.2	12.713 h
October	13.7°C9.7°C	9.7°C	143	16.7	10.711 h
November	10.5°C6.9°C	6.9°C	143	17.3	8.99 h
December, selected	8.2°C4.7°C	4.7°C	145	16.8	7.98 h

Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.

Compare places

December in nearby cities

Distance from Swansea

Read the numbers correctly

Climate, not a promise.

These patterns help compare months. They cannot tell you the weather on a specific day of your trip.

Sources, method and limits

How these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Swansea) is explained once on the Swansea year overview and on the Sources, method and limits page.