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September Weather in Brookhaven, United States

Last updated: June 24, 2025

In Brookhaven, United States, the average temperature in September hovers around 20°C (68°F), making it a pleasant time to visit. Expect minimums to dip to 5°C (41°F) and maximums to soar up to 32°C (90°F). During this month, anticipate 114 mm (4.5 in) of precipitation spread over 9 days, contributing to an average humidity of 73%. Plan accordingly for a comfortable experience!

September Temperature in Brookhaven

In September in Brookhaven, the average temperature is 20°C (68°F). Maximums can reach 32°C (90°F), and minimums can dip as low as 5°C (41°F). This variety in temperatures makes it a great time for travelers to enjoy both warm days and cooler nights.

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

The chart illustrates September temperature patterns in Brookhaven, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Brookhaven, September typically has an average temperature of 20°C (68°F), with highs reaching up to 32°C (90°F) and lows dropping to around 5°C (41°F).
JanFebMarAprMayJunJulAugSepOctNovDec333743526369747267574338
Data source: Temperature data for Brookhaven 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 Brookhaven

In Brookhaven in September, the precipitation amount is 114 mm (4.5 in) over the course of 9 days.

September Precipitation Trends in Brookhaven

The chart displays monthly precipitation patterns in Brookhaven, 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 Brookhaven, September typically receives around 114 mm (4.5 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec9315011814515616113011711411790130
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
Choose your preferred precipitation unit

September Humidity in Brookhaven

In Brookhaven in September, humidity is 73%. With an average temperature of 20°C (68°F), this humidity feels like a warm embrace, making outdoor activities somewhat sticky, yet the atmosphere remains pleasant for leisurely strolls and sightseeing.

September Average Humidity in Brookhaven

This chart illustrates the average monthly humidity levels in Brookhaven, 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 Brookhaven is approximately 73%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%88%88%87%82%84%82%73%74%81%89%86%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Brookhaven

In Brookhaven in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Brookhaven.

Maximum UV Index Levels in Brookhaven for September

The chart shows the monthly maximum UV Index (UVI) for Brookhaven 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 Brookhaven typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3579101010108753
Data source: Brookhaven 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 Brookhaven Compares to Other Months

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

This table compares monthly weather conditions in Brookhaven, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather0°C (33°F)93 mm (3.7 inches)88%moderate
February Weather3°C (38°F)150 mm (5.9 inches)88%moderate
March Weather6°C (44°F)118 mm (4.7 inches)88%high
April Weather11°C (53°F)145 mm (5.7 inches)86%very high
May Weather17°C (63°F)156 mm (6.1 inches)82%very high
June Weather21°C (70°F)161 mm (6.3 inches)84%very high
July Weather23°C (74°F)130 mm (5.1 inches)82%very high
August Weather22°C (72°F)117 mm (4.6 inches)73%very high
September Weather20°C (68°F)114 mm (4.5 inches)73%very high
October Weather14°C (58°F)117 mm (4.6 inches)81%high
November Weather6°C (43°F)90 mm (3.5 inches)89%moderate
December Weather3°C (38°F)130 mm (5.1 inches)86%moderate

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