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September Weather in Fairfield, United States

Last updated: June 24, 2025

In Fairfield, United States, the average temperature in September hovers around 16°C (61°F). However, temperatures can fluctuate significantly, with a minimum of -2°C (29°F) and a maximum of 36°C (97°F). During this month, expect about 18 mm (0.7 in) of precipitation spread across 3 days, and enjoy an average humidity level of 46%.

September Temperature in Fairfield

In September in Fairfield, the average temperature is 16°C (61°F). Maximums can reach 36°C (97°F), while minimums can plummet to -2°C (29°F). Be prepared for a wide range of temperatures to ensure a comfortable trip.

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 16°C (61°F), with highs reaching up to 36°C (97°F) and lows dropping to around -2°C (29°F).
JanFebMarAprMayJunJulAugSepOctNovDec242736425264747161453524
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 precipitation amount is 18 mm (0.7 in) over a span of 3 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 18 mm (0.7 inches) of precipitation spread over approximately 3 days.
JanFebMarAprMayJunJulAugSepOctNovDec63755435481741518344848
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 46%. With an average temperature of 16°C (61°F), this humidity feels like a refreshing, mildly cool environment for traveling, where the air is crisp enough to keep you comfortable while exploring the sights without feeling stifling or oppressive.

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 46%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec91%92%85%76%66%62%53%42%46%64%83%87%
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 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 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 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579101111109643
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 Weather-5°C (24°F)62 mm (2.5 inches)91%moderate
February Weather-3°C (27°F)75 mm (3.0 inches)92%moderate
March Weather2°C (36°F)54 mm (2.1 inches)85%high
April Weather6°C (43°F)35 mm (1.4 inches)76%very high
May Weather11°C (53°F)48 mm (1.9 inches)66%very high
June Weather18°C (64°F)17 mm (0.7 inches)62%extreme
July Weather23°C (74°F)4 mm (0.1 inches)53%extreme
August Weather22°C (71°F)15 mm (0.6 inches)42%very high
September Weather16°C (61°F)18 mm (0.7 inches)46%very high
October Weather7°C (45°F)34 mm (1.3 inches)64%high
November Weather1°C (35°F)48 mm (1.9 inches)83%moderate
December Weather-4°C (24°F)48 mm (1.9 inches)87%moderate

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