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The temperatures in Delaware in September are comfortable with low of 17°C and and high up to 25°C.
You can expect about 3 to 8 days of rain in Delaware 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 Delaware in September 2025.
If you’re planning to visit Delaware in the near future, we highly recommend that you review the 14 day weather forecast for Delaware before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 4° / -2° | 6 | 19 | 6 | 105 mm | Awful | Delaware in January |
| February | 6° / -1° | 7 | 16 | 6 | 136 mm | Awful | Delaware in February |
| March | 10° / 3° | 8 | 20 | 3 | 140 mm | Awful | Delaware in March |
| April | 16° / 8° | 7 | 23 | 0 | 121 mm | Ok | Delaware in April |
| May | 22° / 14° | 8 | 23 | 0 | 153 mm | Ok | Delaware in May |
| June | 26° / 18° | 8 | 22 | 0 | 191 mm | Good | Delaware in June |
| July | 29° / 21° | 10 | 21 | 0 | 208 mm | Ok | Delaware in July |
| August | 28° / 20° | 8 | 23 | 0 | 203 mm | Good | Delaware in August |
| September | 25° / 17° | 6 | 24 | 0 | 139 mm | Perfect | Delaware in September |
| October | 19° / 12° | 6 | 25 | 0 | 173 mm | Good | Delaware in October |
| November | 12° / 6° | 5 | 25 | 0 | 110 mm | Ok | Delaware in November |
| December | 8° / 2° | 7 | 21 | 3 | 154 mm | Awful | Delaware in December |