Month by month
| Month | Afternoon | Sea | Rain | Verdict |
|---|---|---|---|---|
| January | 6.3 °C | — | 14 days | Unfavourable season |
| February | 8.4 °C | — | 12 days | Unfavourable season |
| March | 10.9 °C | — | 14 days | Unfavourable season |
| April | 14.1 °C | — | 11 days | Possible, with trade-offs |
| May | 18.2 °C | — | 12 days | Possible, with trade-offs |
| June | 22 °C | — | 10 days | Pleasant — a good time to go |
| July | 23 °C | — | 11 days | Pleasant — a good time to go |
| August | 23.4 °C | — | 12 days | Pleasant — a good time to go |
| September | 20.2 °C | — | 11 days | Pleasant — a good time to go |
| October | 15.7 °C | — | 13 days | Possible, with trade-offs |
| November | 10.3 °C | — | 14 days | Unfavourable season |
| December | 7.8 °C | — | 14 days | Unfavourable season |
Before you go
Three things to check once you have picked your dates.
Entry
Belgium is in the European Union. Entry rules depend on your nationality — check before booking.
Safety
No specific restrictions
Usual precautions apply.
Official advice updated 12 August 2026
Health
Recommended vaccinations, water quality, mosquitoes: advice depends on the country and the season. Some vaccines need time before departure.
Beau Fixe is not a safety or health authority. These notes summarise public advisories and link to their source; only the competent authorities are authoritative. Alert levels: Foreign, Commonwealth & Development Office (gov.uk), Open Government Licence v3.0.
FAQ
Can you swim in Brussels in September?
Brussels is not a seaside destination (no sea data).
How hot is Brussels in September?
Expect 20.2°C in the afternoon and 12°C at night, averaged over the last 10 years.
Does it rain a lot in Brussels in September?
Around 11 days with rain (≥ 1 mm) in the month — 38% of days.