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September Weather in New Haven, United States

Last updated: June 24, 2025

In New Haven, United States, the average temperature in September hovers around 22°C (72°F). Expect a minimum of 8°C (47°F) and a maximum of 36°C (97°F). The month brings 125 mm (4.9 in) of precipitation over approximately 9 days, creating a humidity level of about 71%. Whether you're basking in the sun or finding shelter from rain, be prepared for a variety of weather experiences!

September Temperature in New Haven

In September in New Haven, the average temperature is 22°C (72°F), with maximums reaching 36°C (97°F) and minimums dropping as low as 8°C (47°F). This weather makes it an ideal time for outdoor activities and exploring the local attractions while enjoying comfortable temperatures.

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 36°C (97°F) and lows dropping to around 8°C (47°F).
JanFebMarAprMayJunJulAugSepOctNovDec374149576875787672614642
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 total precipitation amount is 125 mm (4.9 in) recorded over a span of 9 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 125 mm (4.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec9615013514411915711510412510889121
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 71%. With an average temperature of 22°C (72°F), this humidity feels like the air is thick and slightly stifling, making outdoor activities require frequent breaks to stay hydrated and cool.

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 71%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%86%86%82%83%83%80%74%71%78%88%88%
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.
JanFebMarAprMayJunJulAugSepOctNovDec3579101111109753
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 Weather3°C (37°F)96 mm (3.8 inches)87%moderate
February Weather5°C (41°F)150 mm (5.9 inches)86%moderate
March Weather9°C (49°F)135 mm (5.3 inches)86%high
April Weather14°C (57°F)144 mm (5.7 inches)82%very high
May Weather20°C (68°F)119 mm (4.7 inches)82%very high
June Weather24°C (75°F)157 mm (6.2 inches)83%extreme
July Weather26°C (79°F)115 mm (4.5 inches)80%extreme
August Weather25°C (77°F)104 mm (4.1 inches)74%very high
September Weather22°C (72°F)125 mm (4.9 inches)71%very high
October Weather16°C (61°F)108 mm (4.2 inches)78%high
November Weather8°C (46°F)89 mm (3.5 inches)88%moderate
December Weather6°C (42°F)121 mm (4.8 inches)88%moderate

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