New Haven weather in September
Temperature, sea and sunshine in September: long-term averages from 30 years of weather data, not a forecast.
Holiday weather in September
Good
Best time to visit: July – August
What is the weather like in New Haven in September?
In September, New Haven is warm: daytime highs average 23 °C, and nights cool down to about 17 °C. The sea averages 21.9 °C – refreshing for a swim. Expect around 6 hours of sunshine a day. Rain falls on about 9 days, adding up to 100 mm. All in all, September is a good month for a holiday in New Haven.
September compared
How the weather changes from August to October. Tap a month to open it.
| AugustAug | SeptemberSep | OctoberOct | |
|---|---|---|---|
| Score | 84 | 64 | 25 |
| Day | 26° | 23° | 17° |
| Night | 20° | 17° | 11° |
| Sea | 23° | 22° | 18° |
| Sun | 8 h | 6 h | 6 h |
| Rain days | 10 | 9 | 10 |
More details for September
- Daylight
- 12 h 32 min06:31 – 19:03
- UV index
- 6 · highclear sky, noon (estimate)All months
- Muggy days
- 7 daysdew point 18 °C or moreAll months
- Wind
- 21 km/haverage daily peakAll months
- Cloud cover
- 52 %on averageAll months
- Hot days
- 1 day30 °C or moreAll months
- Snow days
- 0 days1 cm or more of fresh snowAll months
- Time zone
- UTC−4America/New_York
How the score comes together
- Temperatureweight 35 %63 %
- Seaweight 25 %70 %
- Sunshineweight 20 %55 %
- Few rainy daysweight 20 %65 %
Each factor is rated from 0 to 100 % and weighted for the travel style “Sun, sea & sand”.
What to pack in September
- Swimwear
- Sunscreen
- Sunglasses & sun hat
- Rain jacket or umbrella
New Haven in September: quick answers
Is New Haven hot in September?
Warm rather than hot: in September, daytime highs in New Haven average 23 °C and nights cool to about 17 °C.
Can you swim in New Haven in September?
Yes. In September the sea averages 21.9 °C – refreshing for a swim.
Does it rain much in New Haven in September?
Rain falls on about 9 days, adding up to 100 mm.
New Haven month by month
The whole year in New HavenAll destinations: USAWhere to go in SeptemberSea temperature in September
Climate averages 1996–2025, not a forecast. Data: Copernicus ERA5 / ERA5-Land via Open-Meteo.com (CC BY 4.0), NOAA OISST, WMO 1991–2020 (NOAA NCEI), GeoNames (CC BY 4.0). Sources & licences