Cardiff weather by month
Cardiff runs from about 5°C in January to 17°C in August, with February the wettest month at 211 mm.
warmest month
August
17°C
coolest month
January
5°C
wettest month
February
211 mm
worst air month
March
11 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 5°C | 87 mm | 134 h | 5 |
| February | 8°C | 211 mm | 96 h | 5 |
| March | 8°C | 161 mm | 197 h | 11 |
| April | 10°C | 149 mm | 229 h | 8 |
| May | 14°C | 128 mm | 336 h | 8 |
| June | 15°C | 49 mm | 377 h | 6 |
| July | 16°C | 90 mm | 329 h | 5 |
| August | 17°C | 81 mm | 290 h | 6 |
| September | 14°C | 196 mm | 230 h | 5 |
| October | 12°C | 161 mm | 197 h | 6 |
| November | 9°C | 104 mm | 101 h | 4 |
| December | 8°C | 101 mm | 80 h | 5 |
About 2,596 hours of sun a year. Roughly 152 rainy days a year.
These are long-run climate normals, not a forecast. A given year can sit well outside them. PM2.5 is a global model: near the coast it counts sea salt as fine particulate and reads high against ground stations, sometimes by a factor of two. Use the shape of the year, not the absolute number.
where these numbers come from
- · Temperature, rainfall and sunshine: ECMWF ERA5 reanalysis climate normals via Open-Meteo (CC BY 4.0), fetched once and stored.
- · PM2.5: Copernicus CAMS reanalysis, monthly means. Modelled, not station readings; near coasts CAMS counts sea salt as PM2.5 and reads high.
Last reviewed 2026-05-23. Full method, licences and the list of sources we rejected are on the methodology page.