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September Weather in Fairfield, United States

Last updated: June 24, 2025

In September, the average temperature in Fairfield, United States is a pleasant 17°C (62°F). During this time, temperatures can range from a cool 2°C (35°F) to a warm 35°C (95°F). With an average humidity of 62%, you can expect a balanced level of moisture in the air. Additionally, anticipate approximately 32 mm (1.2 in) of precipitation over the course of 4 days, making it a uniquely dynamic month!

September Temperature in Fairfield

In September in Fairfield, the average temperature is 17°C (62°F), with maximums reaching 35°C (95°F) and minimums dropping as low as 2°C (35°F). Be prepared for a wide range of temperatures while traveling, ensuring you pack both light and warmer clothing.

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

The chart illustrates September temperature patterns in Fairfield, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Fairfield, September typically has an average temperature of 17°C (62°F), with highs reaching up to 35°C (95°F) and lows dropping to around 2°C (35°F).
JanFebMarAprMayJunJulAugSepOctNovDec323140475765747362483932
Data source: Temperature data for Fairfield 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 Fairfield

In Fairfield in September, the total precipitation amount is 32 mm (1.2 in) over a span of 4 days.

September Precipitation Trends in Fairfield

The chart displays monthly precipitation patterns in Fairfield, 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 Fairfield, September typically receives around 32 mm (1.2 inches) of precipitation spread over approximately 4 days.
JanFebMarAprMayJunJulAugSepOctNovDec7675635753243932618978
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Fairfield

In Fairfield in September, humidity is 62%. With an average temperature of 17°C (62°F), this humidity feels like a warm embrace, making it a comfortable yet slightly muggy environment for traveling, perfect for leisurely strolls but possibly requiring light clothing adjustments.

September Average Humidity in Fairfield

This chart illustrates the average monthly humidity levels in Fairfield, 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 Fairfield is approximately 62%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec89%89%87%84%78%78%77%64%62%79%87%90%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Fairfield

In Fairfield in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Fairfield.

Maximum UV Index Levels in Fairfield for September

The chart shows the monthly maximum UV Index (UVI) for Fairfield 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 Fairfield typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2456891097532
Data source: Fairfield 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 Fairfield Compares to Other Months

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

This table compares monthly weather conditions in Fairfield, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (32°F)76 mm (3.0 inches)89%low
February Weather-1°C (31°F)75 mm (3.0 inches)89%moderate
March Weather4°C (40°F)63 mm (2.5 inches)87%moderate
April Weather8°C (47°F)57 mm (2.2 inches)84%high
May Weather14°C (57°F)53 mm (2.1 inches)77%very high
June Weather19°C (66°F)24 mm (1.0 inches)78%very high
July Weather23°C (74°F)3 mm (0.1 inches)77%very high
August Weather23°C (73°F)9 mm (0.3 inches)64%very high
September Weather17°C (62°F)32 mm (1.2 inches)62%high
October Weather9°C (48°F)61 mm (2.4 inches)79%moderate
November Weather4°C (39°F)89 mm (3.5 inches)87%moderate
December Weather0°C (33°F)78 mm (3.1 inches)90%low

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