Swansea climate
Swansea (Wales, United Kingdom) has a temperate oceanic climate (Köppen Cfb). The average temperature over the year is 11 °C52 °F, and about 1,105 mm43 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Swansea climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin | Frost days |
|---|---|---|---|---|---|
| Jan | 846 | 541 | 644 | 1124.4 | 2 |
| Feb | 846 | 440 | 643 | 873.4 | 1 |
| Mar | 949 | 540 | 745 | 803.1 | 1 |
| Apr | 1254 | 644 | 949 | 602.4 | 0 |
| May | 1559 | 949 | 1254 | 712.8 | 0 |
| Jun | 1864 | 1254 | 1559 | 773.0 | 0 |
| Jul | 1966 | 1457 | 1762 | 873.4 | 0 |
| Aug | 1966 | 1458 | 1762 | 943.7 | 0 |
| Sep | 1864 | 1355 | 1559 | 753.0 | 0 |
| Oct | 1558 | 1151 | 1355 | 1154.5 | 0 |
| Nov | 1152 | 846 | 1049 | 1214.8 | 0 |
| Dec | 948 | 642 | 745 | 1254.9 | 1 |
| Year | 1966 | 440 | 1152 | 1,10543 | 6 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total. Frost days are for the whole grid cell.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 91% | 80% | 0.8 | 8:18 |
| Feb | 90% | 79% | 1.5 | 9:53 |
| Mar | 88% | 75% | 2.7 | 11:42 |
| Apr | 85% | 69% | 4.1 | 13:48 |
| May | 83% | 70% | 5.0 | 15:36 |
| Jun | 84% | 71% | 5.3 | 16:38 |
| Jul | 84% | 70% | 5.0 | 16:12 |
| Aug | 85% | 73% | 4.2 | 14:36 |
| Sep | 85% | 70% | 3.2 | 12:33 |
| Oct | 87% | 76% | 1.8 | 10:33 |
| Nov | 89% | 81% | 1.0 | 8:45 |
| Dec | 91% | 82% | 0.6 | 7:50 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Swansea is like
The warmest month is August, with an average high of 19 °C66 °F and a low of 14 °C58 °F. The coldest is February, when highs average 8 °C46 °F and lows 4 °C40 °F. There is a clear seasonal cycle, with 10.6 °C19.1 °F between the average temperature of the warmest and the coolest month.
It is wet, with about 1,105 mm43 in of precipitation per year. The wettest three-month stretch is October–December, which brings 33% of the annual total. The wettest month is December (125 mm4.9 in), the driest is April (60 mm2.4 in).
Relative humidity ranges from 83% in May to 91% in January. The clearest skies (lowest average cloud amount, 69%) are typical of April. Average wind speed near the ground ranges from 13 km/h (8 mph) in June to 19 km/h (12 mph) in January. Daylight lasts from about 7.8 hours in December to 16.6 hours in June.
Best time to visit Swansea
Based on these averages, the most comfortable months for sightseeing and outdoor activities are June–September: average highs of 18 °C64 °F to 19 °C66 °F with 75 mm3.0 in to 94 mm3.7 in of precipitation per month.
The most challenging month is December, which is cold, with average highs of 9 °C48 °F.
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
What to pack for Swansea
- Winter (December–February) — highs 846 to 9 °C48 °F, lows 440 to 6 °C42 °F, about 108 mm4.3 in of precipitation a month. Pack a warm coat, layers and closed shoes and an umbrella or light rain jacket.
- Spring (March–May) — highs 949 to 15 °C59 °F, lows 540 to 9 °C49 °F, about 70 mm2.8 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket.
- Summer (June–August) — highs 1864 to 19 °C66 °F, lows 1254 to 14 °C58 °F, about 86 mm3.4 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket.
- Autumn (September–November) — highs 1152 to 18 °C64 °F, lows 846 to 13 °C55 °F, about 104 mm4.1 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket and an umbrella or light rain jacket.
How Swansea compares
Compared with Cardiff, about 55 km to the east, Swansea has practically the same average temperature and receives 14% more precipitation (1,105 mm43 in vs 967 mm38 in). The difference is largest in December (0.9 °C1.6 °F warmer).
Of the 66 places in the United Kingdom covered by World Climates, Swansea is the 10th warmest by annual mean temperature and the 8th wettest by annual precipitation. See all of them on the United Kingdom climate page.
Places in other countries with the most similar temperature and rainfall pattern: Cork (Ireland, Cfb), Limerick (Ireland, Cfb) and Dublin (Ireland, Cfb).
Nearby places
- Cardiff 55 km · 11 °C52 °F · 967 mm38 in
- Newport 65 km · 11 °C52 °F · 967 mm38 in
- Bristol 95 km · 11 °C51 °F · 811 mm32 in
- Exeter 104 km · 11 °C52 °F · 1,087 mm43 in
- Gloucester 120 km · 10 °C51 °F · 772 mm30 in
- Cheltenham 132 km · 10 °C50 °F · 791 mm31 in
- Worcester 134 km · 10 °C50 °F · 772 mm30 in
- Plymouth 140 km · 11 °C53 °F · 1,164 mm46 in
Frequently asked questions
What is the warmest month in Swansea?
August is the warmest month in Swansea, with an average high of 19 °C (66 °F) and an average low of 14 °C (58 °F).
What is the coldest month in Swansea?
February is the coldest month, with an average high of 8 °C (46 °F) and an average low of 4 °C (40 °F).
When does it rain the most in Swansea?
December is the wettest month with about 125 mm (4.9 in) of precipitation; April is the driest with about 60 mm (2.4 in).
What is the best time to visit Swansea?
Judging by long-term averages, the most comfortable months are June–September.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.
The grid cell’s average elevation is 69 m, while Swansea lies at about 18 m. Temperatures on this page were therefore adjusted by +0.3 °C0.6 °F using the standard lapse rate of 6.5 °C per 1,000 m.