Galway weather by month
Galway runs from about 5°C in January to 15°C in August, with August the wettest month at 180 mm.
warmest month
August
15°C
coolest month
January
5°C
wettest month
August
180 mm
worst air month
August
6 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 5°C | 107 mm | 119 h | 4 |
| February | 8°C | 133 mm | 121 h | 5 |
| March | 8°C | 157 mm | 165 h | 5 |
| April | 10°C | 125 mm | 226 h | 5 |
| May | 13°C | 85 mm | 274 h | 4 |
| June | 13°C | 58 mm | 275 h | 4 |
| July | 15°C | 92 mm | 287 h | 4 |
| August | 15°C | 180 mm | 276 h | 6 |
| September | 13°C | 37 mm | 223 h | 3 |
| October | 12°C | 140 mm | 171 h | 5 |
| November | 9°C | 109 mm | 79 h | 3 |
| December | 8°C | 106 mm | 79 h | 5 |
About 2,295 hours of sun a year. Roughly 135 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.