Click on a day for an hourly weather forecast
The temperatures in Posio in September are quite cold with temperatures between 5°C and 11°C, warm clothes are a must.
You can expect rain for roughly half of the month of September in Posio. We’re expecting roughly 8 to 15 days of rain, so your rubber boots and umbrella are going to see plenty of use this month if you’re keen on staying dry.
Please note that Posio can expect a few days of snow in September.
Our weather forecast can give you a great sense of what weather to expect in Posio in September 2025.
If you’re planning to visit Posio in the near future, we highly recommend that you review the 14 day weather forecast for Posio before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -9° / -14° | 1 | 4 | 25 | 62 mm | Awful | Posio in January |
| February | -8° / -13° | 1 | 4 | 24 | 59 mm | Awful | Posio in February |
| March | -4° / -10° | 3 | 4 | 25 | 63 mm | Awful | Posio in March |
| April | 1° / -4° | 6 | 4 | 23 | 73 mm | Awful | Posio in April |
| May | 10° / 2° | 7 | 15 | 9 | 81 mm | Awful | Posio in May |
| June | 16° / 7° | 8 | 21 | 1 | 106 mm | Ok | Posio in June |
| July | 19° / 10° | 9 | 22 | 0 | 124 mm | Ok | Posio in July |
| August | 16° / 8° | 8 | 23 | 0 | 125 mm | Ok | Posio in August |
| September | 11° / 5° | 8 | 20 | 2 | 89 mm | Awful | Posio in September |
| October | 3° / -1° | 8 | 10 | 14 | 93 mm | Awful | Posio in October |
| November | -2° / -5° | 6 | 3 | 23 | 80 mm | Awful | Posio in November |
| December | -6° / -10° | 2 | 3 | 27 | 70 mm | Awful | Posio in December |