Brno weather by month
Brno runs from about 0°C in January to 23°C in August, with September the wettest month at 207 mm.
warmest month
August
23°C
coolest month
January
0°C
wettest month
September
207 mm
worst air month
December
28 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 0°C | 54 mm | 164 h | 24 |
| February | 7°C | 45 mm | 137 h | 20 |
| March | 8°C | 52 mm | 245 h | 19 |
| April | 12°C | 31 mm | 284 h | 11 |
| May | 16°C | 94 mm | 349 h | 8 |
| June | 20°C | 88 mm | 369 h | 7 |
| July | 23°C | 24 mm | 394 h | 5 |
| August | 23°C | 38 mm | 375 h | 7 |
| September | 17°C | 207 mm | 253 h | 6 |
| October | 11°C | 42 mm | 201 h | 7 |
| November | 4°C | 18 mm | 155 h | 22 |
| December | 1°C | 33 mm | 96 h | 28 |
About 3,022 hours of sun a year. Roughly 72 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.