Click on a day for an hourly weather forecast
The temperatures in New Haven in September are comfortable with low of 16°C and and high up to 24°C.
You can expect about 3 to 8 days of rain in New Haven 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 Haven in September 2025.
If you’re planning to visit New Haven in the near future, we highly recommend that you review the 14 day weather forecast for New Haven before you arrive.
| Month | Temperatures | Rainy Days | Dry Days | Snowy Days | Rainfall | Weather | More details |
|---|---|---|---|---|---|---|---|
| January | 2° / -4° | 7 | 15 | 9 | 130 mm | Awful | New Haven in January |
| February | 3° / -3° | 7 | 12 | 10 | 145 mm | Awful | New Haven in February |
| March | 7° / 0° | 8 | 17 | 6 | 153 mm | Awful | New Haven in March |
| April | 13° / 6° | 8 | 21 | 1 | 145 mm | Bad | New Haven in April |
| May | 19° / 11° | 8 | 23 | 0 | 143 mm | Ok | New Haven in May |
| June | 24° / 16° | 8 | 22 | 0 | 154 mm | Good | New Haven in June |
| July | 28° / 20° | 8 | 23 | 0 | 179 mm | Good | New Haven in July |
| August | 27° / 20° | 7 | 24 | 0 | 170 mm | Good | New Haven in August |
| September | 24° / 16° | 6 | 24 | 0 | 122 mm | Perfect | New Haven in September |
| October | 17° / 11° | 7 | 24 | 0 | 175 mm | Ok | New Haven in October |
| November | 11° / 5° | 7 | 22 | 1 | 121 mm | Bad | New Haven in November |
| December | 5° / 0° | 8 | 17 | 6 | 169 mm | Awful | New Haven in December |