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September Weather in New Haven, United States

Last updated: June 24, 2025

In September, the average temperature in New Haven, United States is a pleasant 22°C (72°F). However, be prepared for a range of temperatures, with minimums dipping to 8°C (46°F) and highs reaching up to 35°C (96°F). During this month, you can expect around 52 mm (2.0 in) of precipitation over 6 days, contributing to the average humidity of 76%.

September Temperature in New Haven

In September in New Haven, the average temperature is 22°C (72°F). Maximums can reach 35°C (96°F), and minimums can be as low as 8°C (46°F). This varied climate makes it a perfect destination for travelers seeking both warmth and cooler evenings.

September Weather in New Haven: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in New Haven, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In New Haven, September typically has an average temperature of 22°C (72°F), with highs reaching up to 35°C (96°F) and lows dropping to around 8°C (46°F).
JanFebMarAprMayJunJulAugSepOctNovDec333647556676797672584539
Data source: Temperature data for New Haven generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in New Haven

In New Haven, in September, the precipitation amount is 52 mm (2.0 in) over the course of 6 days.

September Precipitation Trends in New Haven

The chart displays monthly precipitation patterns in New Haven, with values for each month alongside September’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how September’s conditions compare to those of other months. In New Haven, September typically receives around 52 mm (2.0 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec747912812816187102141521046751
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in New Haven

In New Haven in September humidity is 76%. With an average temperature of 22°C (72°F), this humidity feels like a warm embrace, making travel slightly uncomfortable as you navigate through the thick, saturated air.

September Average Humidity in New Haven

This chart illustrates the average monthly humidity levels in New Haven, with September’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In September, average humidity in New Haven is approximately 76%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%80%80%80%82%83%81%80%76%76%85%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in New Haven

In New Haven in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in New Haven.

Maximum UV Index Levels in New Haven for September

The chart shows the monthly maximum UV Index (UVI) for New Haven in September, representing the highest UV radiation level. The UVI measures the intensity of ultraviolet radiation from the sun, indicating the potential risk of sunburn and UV-related health issues. In September, the maximum UV index in New Haven typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3569101111109753
Data source: New Haven September UVI data generated using information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

How September Weather in New Haven Compares to Other Months

Weather in New Haven varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in New Haven, focusing on differences in temperature, rainfall, humidity, and UV levels.

This table compares monthly weather conditions in New Haven, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)74 mm (2.9 inches)82%moderate
February Weather2°C (36°F)79 mm (3.1 inches)80%moderate
March Weather8°C (47°F)128 mm (5.1 inches)80%high
April Weather13°C (55°F)128 mm (5.0 inches)80%very high
May Weather19°C (66°F)161 mm (6.3 inches)82%very high
June Weather24°C (76°F)87 mm (3.4 inches)83%extreme
July Weather26°C (79°F)102 mm (4.0 inches)81%extreme
August Weather24°C (76°F)141 mm (5.5 inches)80%very high
September Weather22°C (72°F)52 mm (2.0 inches)76%very high
October Weather15°C (59°F)104 mm (4.1 inches)76%high
November Weather7°C (45°F)67 mm (2.6 inches)85%moderate
December Weather4°C (39°F)51 mm (2.0 inches)86%moderate

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