Click on a day for an hourly weather forecast
The temperatures in Portland in May are quite cold with temperatures between 9°C and 15°C, warm clothes are a must.
You can expect about 3 to 8 days of rain in Portland during the month of May. 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 Portland in May 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 |