Click on a day for an hourly weather forecast
The temperatures in Rockville in September are comfortable with low of 17°C and and high up to 26°C.
You can expect rain for roughly half of the month of September in Rockville. We’re expecting roughly 8 to 15 days of rain, so your rubber boots and umbrella are going to see plenty of use this month if you’re keen on staying dry.
Our weather forecast can give you a great sense of what weather to expect in Rockville in September 2025.
If you’re planning to visit Rockville in the near future, we highly recommend that you review the 14 day weather forecast for Rockville before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 4° / -3° | 7 | 21 | 3 | 79 mm | Awful | Rockville in January |
| February | 7° / -1° | 8 | 17 | 4 | 87 mm | Awful | Rockville in February |
| March | 12° / 2° | 7 | 22 | 2 | 95 mm | Awful | Rockville in March |
| April | 18° / 8° | 8 | 22 | 0 | 116 mm | Ok | Rockville in April |
| May | 23° / 13° | 10 | 21 | 0 | 117 mm | Good | Rockville in May |
| June | 28° / 18° | 10 | 20 | 0 | 119 mm | Good | Rockville in June |
| July | 31° / 21° | 11 | 20 | 0 | 132 mm | Ok | Rockville in July |
| August | 30° / 20° | 12 | 19 | 0 | 122 mm | Ok | Rockville in August |
| September | 26° / 17° | 8 | 22 | 0 | 125 mm | Good | Rockville in September |
| October | 19° / 11° | 7 | 24 | 0 | 119 mm | Ok | Rockville in October |
| November | 12° / 4° | 5 | 25 | 0 | 84 mm | Ok | Rockville in November |
| December | 8° / 1° | 7 | 22 | 2 | 111 mm | Awful | Rockville in December |