Rotterdam weather by month
Rotterdam runs from about 4°C in January to 19°C in August, with May the wettest month at 141 mm.
warmest month
August
19°C
coolest month
January
4°C
wettest month
May
141 mm
worst air month
March
16 µg/m³
The whole year, month by month.
| Month | Avg temp | Rain | Sun | PM2.5 |
|---|---|---|---|---|
| January | 4°C | 65 mm | 125 h | 14 |
| February | 8°C | 123 mm | 100 h | 11 |
| March | 9°C | 66 mm | 196 h | 16 |
| April | 11°C | 107 mm | 278 h | 10 |
| May | 15°C | 141 mm | 338 h | 10 |
| June | 15°C | 72 mm | 349 h | 8 |
| July | 18°C | 111 mm | 329 h | 8 |
| August | 19°C | 57 mm | 354 h | 9 |
| September | 16°C | 123 mm | 269 h | 9 |
| October | 12°C | 59 mm | 188 h | 8 |
| November | 8°C | 105 mm | 110 h | 10 |
| December | 6°C | 79 mm | 60 h | 11 |
About 2,696 hours of sun a year. Roughly 112 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.