Click on a day for an hourly weather forecast
The temperatures in Portland in September are usually low and can range between 13°C and 20°C.
The wather in Portland in September can vary between cold and nice weather days. Expect a few rainy days but usually not more than 3.
Our weather forecast can give you a great sense of what weather to expect in Portland in September 2025.
If you’re planning to visit Portland in the near future, we highly recommend that you review the 14 day weather forecast for Portland before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | -1° / -6° | 4 | 17 | 10 | 43 mm | Awful | Portland in January |
| February | 0° / -5° | 5 | 13 | 10 | 50 mm | Awful | Portland in February |
| March | 4° / -2° | 6 | 18 | 7 | 52 mm | Awful | Portland in March |
| April | 9° / 3° | 5 | 23 | 2 | 50 mm | Bad | Portland in April |
| May | 15° / 9° | 5 | 27 | 0 | 50 mm | Good | Portland in May |
| June | 19° / 13° | 4 | 26 | 0 | 60 mm | Good | Portland in June |
| July | 23° / 16° | 3 | 28 | 0 | 55 mm | Perfect | Portland in July |
| August | 23° / 17° | 3 | 28 | 0 | 53 mm | Perfect | Portland in August |
| September | 20° / 13° | 2 | 28 | 0 | 37 mm | Good | Portland in September |
| October | 14° / 9° | 5 | 26 | 0 | 60 mm | Good | Portland in October |
| November | 8° / 3° | 5 | 23 | 2 | 44 mm | Bad | Portland in November |
| December | 3° / -2° | 6 | 19 | 7 | 58 mm | Awful | Portland in December |