Click on a day for an hourly weather forecast
The temperatures in Belfast in September are usually low and can range between 10°C and 16°C.
You can expect about 3 to 8 days of rain in Belfast 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 Belfast in September 2025.
If you’re planning to visit Belfast in the near future, we highly recommend that you review the 14 day weather forecast for Belfast before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 7° / 3° | 11 | 17 | 4 | 105 mm | Awful | Belfast in January |
| February | 7° / 3° | 11 | 13 | 5 | 113 mm | Awful | Belfast in February |
| March | 9° / 3° | 10 | 19 | 2 | 99 mm | Awful | Belfast in March |
| April | 11° / 5° | 7 | 22 | 1 | 82 mm | Bad | Belfast in April |
| May | 14° / 7° | 8 | 23 | 0 | 97 mm | Ok | Belfast in May |
| June | 16° / 10° | 8 | 22 | 0 | 121 mm | Ok | Belfast in June |
| July | 17° / 11° | 9 | 22 | 0 | 130 mm | Ok | Belfast in July |
| August | 17° / 11° | 10 | 21 | 0 | 149 mm | Ok | Belfast in August |
| September | 16° / 10° | 7 | 23 | 0 | 99 mm | Ok | Belfast in September |
| October | 13° / 8° | 10 | 21 | 0 | 132 mm | Bad | Belfast in October |
| November | 9° / 6° | 9 | 20 | 1 | 123 mm | Bad | Belfast in November |
| December | 7° / 4° | 9 | 20 | 2 | 110 mm | Awful | Belfast in December |