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September Weather in Forest Park, United States

Last updated: June 24, 2025

In September, the average temperature in Forest Park, United States hovers around 24°C (76°F). Expect a dip to a minimum of 8°C (47°F) and a high of 37°C (99°F). During this period, the area receives about 85 mm (3.3 in) of precipitation over approximately 7 days, with an average humidity of 64%.

September Temperature in Forest Park

In September in Forest Park, the average temperature is 24°C (76°F). Maximums can reach 37°C (99°F), while minimums can dip to as low as 8°C (47°F). Be sure to pack accordingly, as the weather can vary significantly, making it essential to dress in layers.

September Weather in Forest Park: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Forest Park, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Forest Park, September typically has an average temperature of 24°C (76°F), with highs reaching up to 37°C (99°F) and lows dropping to around 8°C (47°F).
JanFebMarAprMayJunJulAugSepOctNovDec394154596979838175625044
Data source: Temperature data for Forest Park 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 Forest Park

In Forest Park in September, the total precipitation amount is 85 mm (3.3 in) over the course of 7 days.

September Precipitation Trends in Forest Park

The chart displays monthly precipitation patterns in Forest Park, 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 Forest Park, September typically receives around 85 mm (3.3 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec474684124137966567851083036
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Forest Park

In Forest Park in September, humidity is 64%. With an average temperature of 24°C (76°F), this humidity feels like a warm, sticky embrace, making travel slightly uncomfortable but still enjoyable, as you may find yourself yearning for a refreshing breeze or a quick dip in the water.

September Average Humidity in Forest Park

This chart illustrates the average monthly humidity levels in Forest Park, 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 Forest Park is approximately 64%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec76%76%70%72%82%82%80%72%64%71%81%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Forest Park

In Forest Park 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 Forest Park.

Maximum UV Index Levels in Forest Park for September

The chart shows the monthly maximum UV Index (UVI) for Forest Park 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 Forest Park typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec46810101111119754
Data source: Forest Park 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 Forest Park Compares to Other Months

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

This table compares monthly weather conditions in Forest Park, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather4°C (39°F)47 mm (1.8 inches)76%moderate
February Weather5°C (41°F)46 mm (1.8 inches)76%high
March Weather12°C (54°F)84 mm (3.3 inches)70%very high
April Weather15°C (59°F)124 mm (4.9 inches)72%very high
May Weather21°C (70°F)137 mm (5.4 inches)82%very high
June Weather26°C (79°F)96 mm (3.8 inches)82%extreme
July Weather28°C (83°F)65 mm (2.6 inches)80%extreme
August Weather27°C (81°F)67 mm (2.6 inches)72%extreme
September Weather24°C (76°F)85 mm (3.3 inches)64%very high
October Weather17°C (62°F)108 mm (4.3 inches)71%high
November Weather10°C (50°F)30 mm (1.2 inches)81%moderate
December Weather7°C (44°F)36 mm (1.4 inches)84%moderate

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