Climate averages 1991–2020

Swansea weather
in May.

A cool, moderately wet month: the 5th warmest and the 2nd driest of the year.

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

Average high 14.6°C Daytime mean, May

Average low 8.8°C Night-time mean, May

Rainfall 72 mm 12 days with ≥1 mm

Daylight 16 h Sunrise to sunset, per day

May is a cool month in Swansea: daytime highs average 14.6°C and nights cool to about 8.8°C. By daytime temperature it is the 5th warmest of the 12 months.

Expect about 72 mm of rain on roughly 12 days, which makes May a moderately wet month (the 2nd driest of the 12 months). Daylight, from sunrise to sunset, lasts about 15 h 36 min on an average May day.

The nearest other city in this atlas is Cardiff (55 km away). In May its highs average 15.2°C, 0.6°C warmer than Swansea, with 73 mm of rain.

Among the 143 cities listed in the United Kingdom, Swansea ranks joint 108th of 143 for the warmest May highs and 131st of 143 for the driest May (rainfall, lowest first). The mean May high of those 143 cities is 15.2°C; Swansea is 0.6°C cooler than that mean.

From May to June, average highs rise by 2.3°C to 16.9°C, and monthly rainfall rises from 72 mm to 79 mm.

The annual picture

May 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, selected	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	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

May 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.