Click on a day for an hourly weather forecast
The temperatures in New Castle in September are comfortable with low of 12°C and and high up to 24°C.
You can expect about 3 to 8 days of rain in New Castle 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 New Castle in September 2025.
If you’re planning to visit New Castle in the near future, we highly recommend that you review the 14 day weather forecast for New Castle before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 0° / -8° | 7 | 4 | 21 | 126 mm | Awful | New Castle in January |
| February | 2° / -7° | 7 | 4 | 18 | 126 mm | Awful | New Castle in February |
| March | 8° / -2° | 9 | 12 | 10 | 136 mm | Awful | New Castle in March |
| April | 14° / 4° | 11 | 15 | 5 | 178 mm | Bad | New Castle in April |
| May | 22° / 9° | 10 | 21 | 0 | 172 mm | Ok | New Castle in May |
| June | 26° / 13° | 9 | 21 | 0 | 185 mm | Good | New Castle in June |
| July | 28° / 16° | 10 | 21 | 0 | 183 mm | Good | New Castle in July |
| August | 28° / 15° | 8 | 23 | 0 | 134 mm | Good | New Castle in August |
| September | 24° / 12° | 6 | 24 | 0 | 130 mm | Perfect | New Castle in September |
| October | 17° / 6° | 8 | 23 | 0 | 130 mm | Ok | New Castle in October |
| November | 9° / 0° | 7 | 16 | 7 | 105 mm | Awful | New Castle in November |
| December | 4° / -3° | 9 | 8 | 15 | 130 mm | Awful | New Castle in December |