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September Weather in Brentwood, United States

Last updated: June 24, 2025

In Brentwood, United States, the average temperature in September hovers around 21°C (70°F), providing a pleasant climate. Temperatures can vary, dipping to a minimum of 10°C (50°F) and soaring up to a maximum of 40°C (105°F). With only 1 mm (0.0 in) of precipitation over 0 days, the weather remains dry, complemented by an average humidity of 55%. Enjoy the delightful conditions this month!

September Temperature in Brentwood

In September in Brentwood, the average temperature is 21°C (70°F). Maximum temperatures can reach as high as 40°C (105°F), while minimums can drop to as low as 10°C (50°F). This variety in temperature makes Brentwood an excellent destination for travelers seeking both warm days and cooler evenings.

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

The chart illustrates September temperature patterns in Brentwood, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Brentwood, September typically has an average temperature of 21°C (70°F), with highs reaching up to 40°C (105°F) and lows dropping to around 10°C (50°F).
JanFebMarAprMayJunJulAugSepOctNovDec505356616570717170645650
Data source: Temperature data for Brentwood 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 Brentwood

In Brentwood in September, the precipitation amount is 1 mm (0.0 in) during a span of 0 days.

September Precipitation Trends in Brentwood

The chart displays monthly precipitation patterns in Brentwood, 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 Brentwood, September typically receives around 1 mm (0.0 inches) of precipitation spread over approximately 0 days.
JanFebMarAprMayJunJulAugSepOctNovDec100877030151001263883
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Brentwood

In Brentwood in September humidity is 55%. With average temperature 21°C (70°F), this humidity feels like a refreshing embrace, making it comfortable for traveling as long as you stay hydrated and take in the sights at a leisurely pace.

September Average Humidity in Brentwood

This chart illustrates the average monthly humidity levels in Brentwood, 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 Brentwood is approximately 55%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%84%82%78%71%64%59%54%55%62%78%80%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Brentwood

In Brentwood 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 Brentwood.

Maximum UV Index Levels in Brentwood for September

The chart shows the monthly maximum UV Index (UVI) for Brentwood 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 Brentwood typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3589101111109643
Data source: Brentwood 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 Brentwood Compares to Other Months

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

This table compares monthly weather conditions in Brentwood, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather10°C (50°F)100 mm (4.0 inches)82%moderate
February Weather11°C (53°F)87 mm (3.4 inches)84%moderate
March Weather13°C (56°F)70 mm (2.7 inches)82%very high
April Weather16°C (61°F)30 mm (1.2 inches)78%very high
May Weather18°C (65°F)15 mm (0.6 inches)71%very high
June Weather21°C (70°F)1 mm (0.1 inches)64%extreme
July Weather22°C (71°F)0 mm (0.0 inches)58%extreme
August Weather22°C (71°F)0 mm (0.0 inches)54%very high
September Weather21°C (70°F)1 mm (0.0 inches)55%very high
October Weather18°C (64°F)26 mm (1.0 inches)62%high
November Weather13°C (56°F)38 mm (1.5 inches)78%moderate
December Weather10°C (50°F)83 mm (3.3 inches)80%moderate

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