Click on a day for an hourly weather forecast
The temperatures in Seinajoki in September are quite cold with temperatures between 7°C and 14°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Seinajoki 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 Seinajoki in September 2026.
If you’re planning to visit Seinajoki in the near future, we highly recommend that you review the 14 day weather forecast for Seinajoki before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -5° / -9° | 3 | 7 | 21 | 50 mm | Awful | Seinajoki in January |
| February | -4° / -9° | 3 | 6 | 20 | 44 mm | Awful | Seinajoki in February |
| March | 0° / -6° | 4 | 8 | 19 | 47 mm | Awful | Seinajoki in March |
| April | 6° / -1° | 7 | 14 | 10 | 56 mm | Awful | Seinajoki in April |
| May | 14° / 5° | 7 | 22 | 2 | 76 mm | Bad | Seinajoki in May |
| June | 19° / 9° | 7 | 23 | 0 | 89 mm | Ok | Seinajoki in June |
| July | 22° / 12° | 8 | 23 | 0 | 110 mm | Ok | Seinajoki in July |
| August | 20° / 11° | 8 | 23 | 0 | 132 mm | Ok | Seinajoki in August |
| September | 14° / 7° | 6 | 23 | 0 | 74 mm | Good | Seinajoki in September |
| October | 7° / 2° | 8 | 18 | 5 | 86 mm | Awful | Seinajoki in October |
| November | 2° / -1° | 8 | 11 | 11 | 80 mm | Awful | Seinajoki in November |
| December | -2° / -6° | 5 | 6 | 20 | 63 mm | Awful | Seinajoki in December |