Click on a day for an hourly weather forecast
The temperatures in Lahti in September are quite cold with temperatures between 8°C and 15°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Lahti 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 Lahti in September 2025.
If you’re planning to visit Lahti in the near future, we highly recommend that you review the 14 day weather forecast for Lahti before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -5° / -9° | 4 | 4 | 24 | 68 mm | Awful | Lahti in January |
| February | -4° / -9° | 3 | 3 | 22 | 62 mm | Awful | Lahti in February |
| March | 0° / -6° | 6 | 6 | 21 | 56 mm | Awful | Lahti in March |
| April | 7° / 0° | 6 | 14 | 10 | 56 mm | Bad | Lahti in April |
| May | 15° / 6° | 6 | 24 | 1 | 67 mm | Good | Lahti in May |
| June | 20° / 10° | 6 | 24 | 0 | 80 mm | Good | Lahti in June |
| July | 22° / 13° | 6 | 25 | 0 | 90 mm | Good | Lahti in July |
| August | 20° / 11° | 4 | 27 | 0 | 68 mm | Good | Lahti in August |
| September | 15° / 8° | 5 | 25 | 0 | 62 mm | Good | Lahti in September |
| October | 7° / 3° | 9 | 18 | 5 | 79 mm | Awful | Lahti in October |
| November | 2° / -1° | 7 | 13 | 10 | 73 mm | Awful | Lahti in November |
| December | -2° / -5° | 6 | 4 | 22 | 75 mm | Awful | Lahti in December |