Click on a day for an hourly weather forecast
The temperatures in Helsinki in September are usually low and can range between 12°C and 15°C.
You can expect about 3 to 8 days of rain in Helsinki 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 Helsinki in September 2025.
If you’re planning to visit Helsinki in the near future, we highly recommend that you review the 14 day weather forecast for Helsinki before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -2° / -5° | 4 | 8 | 19 | 60 mm | Awful | Helsinki in January |
| February | -2° / -5° | 4 | 7 | 17 | 51 mm | Awful | Helsinki in February |
| March | 1° / -3° | 7 | 10 | 15 | 46 mm | Awful | Helsinki in March |
| April | 5° / 2° | 6 | 18 | 6 | 42 mm | Awful | Helsinki in April |
| May | 11° / 7° | 5 | 25 | 1 | 60 mm | Ok | Helsinki in May |
| June | 16° / 12° | 6 | 24 | 0 | 83 mm | Good | Helsinki in June |
| July | 20° / 16° | 6 | 25 | 0 | 106 mm | Good | Helsinki in July |
| August | 19° / 15° | 7 | 24 | 0 | 135 mm | Ok | Helsinki in August |
| September | 15° / 12° | 6 | 24 | 0 | 91 mm | Good | Helsinki in September |
| October | 9° / 6° | 8 | 20 | 3 | 90 mm | Awful | Helsinki in October |
| November | 5° / 3° | 7 | 18 | 5 | 76 mm | Awful | Helsinki in November |
| December | 1° / -1° | 7 | 11 | 14 | 72 mm | Awful | Helsinki in December |