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September Weather in Hartford, United States

Last updated: June 24, 2025

In September, the average temperature in Hartford, United States is a pleasant 23°C (73°F). While you can expect a minimum of 8°C (46°F), temperatures can soar to a maximum of 37°C (99°F). During this month, precipitation averages around 103 mm (4.1 in) over 8 days, contributing to an average humidity of 71%. Prepare accordingly for this diverse weather!

September Temperature in Hartford

In September in Hartford, the average temperature is 23°C (73°F). Maximums can reach 37°C (99°F) and minimums can be as low as 8°C (46°F). This diverse temperature range makes Hartford an ideal destination for travelers looking to enjoy both warm and cool experiences during their visit.

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 23°C (73°F), with highs reaching up to 37°C (99°F) and lows dropping to around 8°C (46°F).
JanFebMarAprMayJunJulAugSepOctNovDec374150586976807873624643
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 precipitation amount is 103 mm (4.1 in) over a span of 8 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 103 mm (4.1 inches) of precipitation spread over approximately 8 days.
JanFebMarAprMayJunJulAugSepOctNovDec931501291491261251039210311593106
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 71%. With an average temperature of 23°C (73°F), this humidity feels like a warm, sticky embrace, making outdoor exploration slightly uncomfortable but still manageable if you stay hydrated and plan for breaks in shaded areas.

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 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 Hartford

In Hartford 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 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec36710101110109753
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 Weather3°C (37°F)93 mm (3.7 inches)87%moderate
February Weather5°C (42°F)150 mm (5.9 inches)86%high
March Weather10°C (50°F)129 mm (5.1 inches)86%high
April Weather14°C (58°F)149 mm (5.9 inches)82%very high
May Weather21°C (70°F)126 mm (5.0 inches)82%very high
June Weather25°C (77°F)125 mm (4.9 inches)83%extreme
July Weather27°C (80°F)103 mm (4.1 inches)80%very high
August Weather25°C (78°F)92 mm (3.6 inches)74%very high
September Weather23°C (73°F)103 mm (4.1 inches)71%very high
October Weather17°C (62°F)115 mm (4.5 inches)78%high
November Weather8°C (47°F)93 mm (3.7 inches)88%moderate
December Weather6°C (43°F)106 mm (4.2 inches)88%moderate

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