Click on a day for an hourly weather forecast
The temperatures in Lewiston in September are comfortable with low of 11°C and and high up to 21°C.
You can expect about 3 to 8 days of rain in Lewiston 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 Lewiston in September 2025.
If you’re planning to visit Lewiston in the near future, we highly recommend that you review the 14 day weather forecast for Lewiston before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -3° / -9° | 4 | 15 | 12 | 108 mm | Awful | Lewiston in January |
| February | -1° / -9° | 4 | 11 | 13 | 113 mm | Awful | Lewiston in February |
| March | 3° / -4° | 7 | 14 | 11 | 124 mm | Awful | Lewiston in March |
| April | 10° / 2° | 8 | 18 | 4 | 134 mm | Awful | Lewiston in April |
| May | 17° / 8° | 8 | 23 | 0 | 110 mm | Ok | Lewiston in May |
| June | 22° / 12° | 7 | 23 | 0 | 134 mm | Ok | Lewiston in June |
| July | 25° / 15° | 6 | 25 | 0 | 104 mm | Perfect | Lewiston in July |
| August | 25° / 15° | 5 | 26 | 0 | 111 mm | Perfect | Lewiston in August |
| September | 21° / 11° | 5 | 25 | 0 | 84 mm | Good | Lewiston in September |
| October | 14° / 6° | 7 | 23 | 0 | 143 mm | Ok | Lewiston in October |
| November | 7° / 0° | 6 | 20 | 4 | 115 mm | Bad | Lewiston in November |
| December | 1° / -4° | 7 | 14 | 10 | 149 mm | Awful | Lewiston in December |