Click on a day for an hourly weather forecast
The temperatures in Manassas in September are comfortable with low of 16°C and and high up to 27°C.
You can expect about 3 to 8 days of rain in Manassas 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 Manassas in September 2025.
If you’re planning to visit Manassas in the near future, we highly recommend that you review the 14 day weather forecast for Manassas before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 5° / -3° | 6 | 19 | 7 | 101 mm | Awful | Manassas in January |
| February | 7° / -2° | 7 | 15 | 6 | 112 mm | Awful | Manassas in February |
| March | 12° / 3° | 8 | 20 | 4 | 126 mm | Awful | Manassas in March |
| April | 19° / 8° | 7 | 23 | 0 | 127 mm | Ok | Manassas in April |
| May | 24° / 13° | 9 | 22 | 0 | 160 mm | Good | Manassas in May |
| June | 29° / 17° | 6 | 24 | 0 | 129 mm | Good | Manassas in June |
| July | 32° / 20° | 6 | 25 | 0 | 132 mm | Good | Manassas in July |
| August | 31° / 19° | 6 | 25 | 0 | 129 mm | Good | Manassas in August |
| September | 27° / 16° | 5 | 25 | 0 | 113 mm | Perfect | Manassas in September |
| October | 20° / 10° | 5 | 26 | 0 | 130 mm | Good | Manassas in October |
| November | 13° / 4° | 5 | 25 | 0 | 95 mm | Ok | Manassas in November |
| December | 8° / 1° | 6 | 21 | 3 | 130 mm | Bad | Manassas in December |