Brussels weather in September
September in Brussels: nice, a little rain, with clean air — an excellent time to visit.
#5 of 12 months in Brussels · #240 of 604 destinations to visit in September · comfort 83/100 (tier A)
Updated June 2026 · climate normals from ERA5 reanalysis
Brussels climate normals — September
| Daytime high | 21°C / 70°F | 😎 nice |
|---|---|---|
| Nighttime low | 13°C / 55°F | |
| Feels like (high) | 20°C / 68°F | |
| Rainfall | 68 mm / 2.7 in | 🌦 some rain |
| Rainy days | 10 days | |
| Humidity | 77% | 💦 very humid |
| Dew point | 13°C / 55°F | |
| Sunshine | 8.9 h/day | |
| Daylight | 12.6 h | |
| Wind | 18 km/h / 11 mph | |
| Air quality (US AQI) | 45 | 🍃 good |
Monthly averages from ERA5 reanalysis. AQI is the mean US Air Quality Index for the month.
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Brussels in September — FAQ
- Is September a good time to visit Brussels?
- September in Brussels: nice, a little rain, with clean air — an excellent time to visit. It ranks #5 of 12 months for Brussels on SeasonMap's comfort score (83/100).
- What is the weather like in Brussels in September?
- In September, Brussels averages a daily high of 20.9°C and a low of 12.7°C, with about 67.6 mm of rain over roughly 9.6 rainy days.
- What is the air quality in Brussels in September?
- Brussels has a mean US Air Quality Index of about 45 in September.