nomadseason

September Weather in Brookhaven, United States

Last updated: June 24, 2025

In September, the average temperature in Brookhaven, United States is a pleasant 26°C (78°F). However, be prepared for a range of temperatures; it can dip as low as 10°C (50°F) and soar up to 38°C (100°F). Rain is a possibility too, with an average precipitation of 110 mm (4.3 in) distributed across 11 days. Plus, expect a relatively high average humidity of 79%, adding to the overall warmth!

September Temperature in Brookhaven

In September in Brookhaven, the average temperature is 26°C (78°F). Maximum temperatures can reach up to 38°C (100°F), while minimums can drop as low as 10°C (50°F). This varied climate makes Brookhaven an ideal destination for travelers seeking both warmth and cooler evenings.

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 26°C (78°F), with highs reaching up to 38°C (100°F) and lows dropping to around 10°C (50°F).
JanFebMarAprMayJunJulAugSepOctNovDec505562657479818078705653
Data source: Temperature data for Brookhaven generated using information from the Copernicus Climate Change Service.
Choose your preferred temperature unit
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 110 mm (4.3 in) spread over 11 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 110 mm (4.3 inches) of precipitation spread over approximately 11 days.
JanFebMarAprMayJunJulAugSepOctNovDec12012912016317514913116911010485139
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 79%. With an average temperature of 26°C (78°F), this humidity feels like a tropical blanket enveloping you, making outdoor activities less comfortable for traveling.

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 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec83%83%80%81%81%78%79%79%79%77%85%88%
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 reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check 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 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec589111112121110864
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 Weather10°C (50°F)120 mm (4.7 inches)83%moderate
February Weather13°C (55°F)129 mm (5.1 inches)83%very high
March Weather16°C (62°F)120 mm (4.7 inches)80%very high
April Weather18°C (65°F)163 mm (6.4 inches)81%extreme
May Weather23°C (74°F)175 mm (6.9 inches)81%extreme
June Weather26°C (79°F)149 mm (5.8 inches)78%extreme
July Weather27°C (81°F)131 mm (5.1 inches)79%extreme
August Weather27°C (80°F)169 mm (6.6 inches)79%extreme
September Weather26°C (78°F)110 mm (4.3 inches)79%very high
October Weather21°C (70°F)104 mm (4.1 inches)77%very high
November Weather14°C (57°F)85 mm (3.4 inches)85%high
December Weather12°C (53°F)139 mm (5.5 inches)88%moderate

Compare Brookhaven's Climate with Cities Worldwide