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September Weather in Hartford, United States

Last updated: June 24, 2025

In Hartford, United States, the average temperature in September hovers around 26°C (79°F). During this time, temperatures can range from a comfortable 13°C (56°F) to a sweltering 39°C (102°F). Precipitation is notable, with about 115 mm (4.5 in) expected over 11 days, and the average humidity sits at a tropical 79%.

September Temperature in Hartford

In September in Hartford, the average temperature is 26°C (79°F), with maximums reaching 39°C (102°F) and minimums dropping as low as 13°C (56°F). Given this range, travelers should pack accordingly to enjoy both warm days and cooler evenings.

September Weather in Hartford: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Hartford, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Hartford, September typically has an average temperature of 26°C (79°F), with highs reaching up to 39°C (102°F) and lows dropping to around 13°C (56°F).
JanFebMarAprMayJunJulAugSepOctNovDec525863677580818179725955
Data source: Temperature data for Hartford 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 Hartford

In Hartford in September, the total precipitation amount is 115 mm (4.5 in) spread over 11 days.

September Precipitation Trends in Hartford

The chart displays monthly precipitation patterns in Hartford, 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 Hartford, September typically receives around 115 mm (4.5 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec90117721081021421321641158343142
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Hartford

In Hartford in September humidity is 79%. With an average temperature of 26°C (79°F), this humidity feels like a warm, sticky embrace that can make outdoor activities feel exhausting. Travelers should be prepared for a heavy air that clings to the skin, making hydration essential while navigating the sights and sounds of the city.

September Average Humidity in Hartford

This chart illustrates the average monthly humidity levels in Hartford, 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 Hartford is approximately 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec83%82%79%77%74%70%78%78%79%74%83%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Hartford

In Hartford in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Hartford.

Maximum UV Index Levels in Hartford for September

The chart shows the monthly maximum UV Index (UVI) for Hartford 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 Hartford typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec589111111121110864
Data source: Hartford 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 Hartford Compares to Other Months

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

This table compares monthly weather conditions in Hartford, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather11°C (52°F)90 mm (3.5 inches)83%moderate
February Weather15°C (59°F)117 mm (4.6 inches)82%very high
March Weather17°C (63°F)71 mm (2.8 inches)79%very high
April Weather19°C (67°F)108 mm (4.3 inches)77%extreme
May Weather24°C (75°F)102 mm (4.0 inches)74%extreme
June Weather26°C (80°F)142 mm (5.6 inches)70%extreme
July Weather27°C (81°F)132 mm (5.2 inches)78%extreme
August Weather27°C (81°F)164 mm (6.4 inches)78%extreme
September Weather26°C (79°F)115 mm (4.5 inches)79%very high
October Weather22°C (72°F)83 mm (3.3 inches)74%very high
November Weather15°C (59°F)43 mm (1.7 inches)83%high
December Weather13°C (55°F)142 mm (5.6 inches)86%moderate

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