Click on a day for an hourly weather forecast
The temperatures in Washington in September are usually low and can range between 10°C and 17°C.
You can expect about 3 to 8 days of rain in Washington 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 Washington in September 2025.
If you’re planning to visit Washington in the near future, we highly recommend that you review the 14 day weather forecast for Washington before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 6° / 2° | 8 | 18 | 5 | 61 mm | Awful | Washington in January |
| February | 7° / 2° | 7 | 15 | 6 | 65 mm | Awful | Washington in February |
| March | 9° / 3° | 6 | 22 | 3 | 54 mm | Bad | Washington in March |
| April | 11° / 4° | 5 | 24 | 1 | 48 mm | Ok | Washington in April |
| May | 14° / 7° | 7 | 24 | 0 | 73 mm | Ok | Washington in May |
| June | 17° / 9° | 7 | 23 | 0 | 89 mm | Ok | Washington in June |
| July | 19° / 12° | 8 | 23 | 0 | 107 mm | Ok | Washington in July |
| August | 19° / 12° | 7 | 24 | 0 | 102 mm | Ok | Washington in August |
| September | 17° / 10° | 5 | 25 | 0 | 61 mm | Good | Washington in September |
| October | 13° / 8° | 8 | 23 | 0 | 79 mm | Bad | Washington in October |
| November | 9° / 5° | 8 | 22 | 1 | 83 mm | Bad | Washington in November |
| December | 6° / 3° | 7 | 21 | 3 | 60 mm | Awful | Washington in December |