Climate averages 1991–2020
New Haven weather
in September.
A warm, wet month: the 4th warmest and the 7th driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
September is a warm month in New Haven: daytime highs average 22.6°C and nights cool to about 16.2°C. By daytime temperature it is the 4th warmest of the 12 months.
Expect about 109 mm of rain on roughly 9 days, which makes September a wet month (the 7th driest of the 12 months). Daylight, from sunrise to sunset, lasts about 12 h 31 min on an average September day.
The nearest other city in this atlas is Bridgeport (26 km away). In September its highs average 22.8°C, about as warm as New Haven, with 103 mm of rain.
Among the 498 cities listed in the United States, New Haven ranks joint 424th of 498 for the warmest September highs and joint 423rd of 498 for the driest September (rainfall, lowest first). The mean September high of those 498 cities is 26.9°C; New Haven is 4.3°C cooler than that mean.
From September to October, average highs fall by 6.0°C to 16.5°C, and monthly rainfall rises from 109 mm to 129 mm.
The annual picture
September in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
New Haven climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 2.7°C-3.6°C | -3.6°C | 108 | 10.1 | 9.610 h |
| February | 3.6°C-3.3°C | -3.3°C | 97 | 9.2 | 10.611 h |
| March | 7.3°C0.0°C | 0.0°C | 128 | 10.9 | 11.912 h |
| April | 13.1°C5.2°C | 5.2°C | 116 | 11.5 | 13.313 h |
| May | 18.4°C10.6°C | 10.6°C | 98 | 11.6 | 14.514 h |
| June | 23.6°C16.2°C | 16.2°C | 98 | 10.5 | 15.115 h |
| July | 27.0°C19.9°C | 19.9°C | 82 | 9.5 | 14.815 h |
| August | 26.3°C19.6°C | 19.6°C | 102 | 9.6 | 13.814 h |
| September, selected | 22.6°C16.2°C | 16.2°C | 109 | 8.9 | 12.513 h |
| October | 16.5°C10.5°C | 10.5°C | 129 | 10.1 | 11.111 h |
| November | 10.7°C4.9°C | 4.9°C | 110 | 9.5 | 9.910 h |
| December | 5.6°C0.0°C | 0.0°C | 137 | 11.2 | 9.39 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
September in nearby cities
- Bridgeport in SeptemberUnited States · 26 kmHigh 22.8°C · Low 16.4°C · 103 mm rain
- Waterbury in SeptemberUnited States · 30 kmHigh 23.2°C · Low 14.6°C · 101 mm rain
- New Britain in SeptemberUnited States · 41 kmHigh 23.3°C · Low 14.1°C · 97 mm rain
- Danbury in SeptemberUnited States · 45 kmHigh 23.0°C · Low 14.6°C · 108 mm rain
- Norwalk in SeptemberUnited States · 45 kmHigh 23.1°C · Low 16.4°C · 94 mm rain
- Hartford in SeptemberUnited States · 55 kmHigh 23.4°C · Low 13.9°C · 97 mm rain
- Stamford in SeptemberUnited States · 58 kmHigh 23.2°C · Low 16.4°C · 94 mm rain
- Greenburgh in SeptemberUnited States · 82 kmHigh 23.3°C · Low 15.9°C · 95 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for New Haven) is explained once on the New Haven year overview and on the Sources, method and limits page.