Click on a day for an hourly weather forecast
The temperatures in Brussels in September are usually low and can range between 12°C and 20°C.
You can expect about 3 to 8 days of rain in Brussels during the month of September. It’s a good idea to bring along your umbrella so that you don’t get caught in poor weather.
Our weather forecast can give you a great sense of what weather to expect in Brussels in September 2025.
If you’re planning to visit Brussels in the near future, we highly recommend that you review the 14 day weather forecast for Brussels before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 5° / 1° | 9 | 16 | 6 | 90 mm | Awful | Brussels in January |
| February | 7° / 2° | 8 | 15 | 6 | 72 mm | Awful | Brussels in February |
| March | 11° / 4° | 7 | 22 | 2 | 72 mm | Awful | Brussels in March |
| April | 15° / 6° | 4 | 25 | 1 | 53 mm | Good | Brussels in April |
| May | 18° / 9° | 6 | 25 | 0 | 87 mm | Good | Brussels in May |
| June | 21° / 12° | 6 | 24 | 0 | 99 mm | Good | Brussels in June |
| July | 23° / 14° | 6 | 25 | 0 | 95 mm | Perfect | Brussels in July |
| August | 23° / 15° | 5 | 26 | 0 | 99 mm | Perfect | Brussels in August |
| September | 20° / 12° | 4 | 26 | 0 | 60 mm | Good | Brussels in September |
| October | 15° / 9° | 5 | 26 | 0 | 71 mm | Good | Brussels in October |
| November | 10° / 5° | 7 | 21 | 1 | 84 mm | Bad | Brussels in November |
| December | 6° / 3° | 9 | 17 | 4 | 103 mm | Awful | Brussels in December |