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September Weather in Willowbrook, United States

Last updated: June 24, 2025

In September, the average temperature in Willowbrook, United States is a pleasant 20°C (68°F), with a comfortable range between a minimum of 3°C (38°F) and a maximum of 34°C (93°F). However, be prepared for about 85 mm (3.4 in) of precipitation spread over 9 days, contributing to an average humidity level of 80%. Enjoy the mild climate, but don't forget your umbrella!

September Temperature in Willowbrook

In September in Willowbrook, the average temperature is 20°C (68°F). Maximums can reach 34°C (93°F), and minimums can be as low as 3°C (38°F). Be prepared for a range of weather conditions during your travels!

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

The chart illustrates September temperature patterns in Willowbrook, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Willowbrook, September typically has an average temperature of 20°C (68°F), with highs reaching up to 34°C (93°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec262839486172757368543933
Data source: Temperature data for Willowbrook 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 Willowbrook

In Willowbrook in September, the total precipitation amount is 85 mm (3.4 in) recorded over a span of 9 days.

September Precipitation Trends in Willowbrook

The chart displays monthly precipitation patterns in Willowbrook, 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 Willowbrook, September typically receives around 85 mm (3.4 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec61638912015615111691851315754
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Willowbrook

In Willowbrook in September, humidity is 80%. With an average temperature of 20°C (68°F), this humidity feels like traveling through a warm, dense blanket that clings to your skin, making you feel both sticky and lethargic as you explore the sights.

September Average Humidity in Willowbrook

This chart illustrates the average monthly humidity levels in Willowbrook, 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 Willowbrook is approximately 80%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec82%83%84%85%79%82%80%81%80%82%88%84%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Willowbrook

In Willowbrook 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 Willowbrook.

Maximum UV Index Levels in Willowbrook for September

The chart shows the monthly maximum UV Index (UVI) for Willowbrook 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 Willowbrook typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689101098642
Data source: Willowbrook 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 Willowbrook Compares to Other Months

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

This table compares monthly weather conditions in Willowbrook, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-3°C (26°F)61 mm (2.4 inches)82%moderate
February Weather-2°C (28°F)63 mm (2.5 inches)83%moderate
March Weather4°C (40°F)89 mm (3.5 inches)84%high
April Weather9°C (49°F)120 mm (4.7 inches)85%very high
May Weather16°C (61°F)156 mm (6.1 inches)79%very high
June Weather22°C (72°F)151 mm (6.0 inches)82%very high
July Weather24°C (76°F)116 mm (4.6 inches)80%very high
August Weather23°C (73°F)91 mm (3.6 inches)81%very high
September Weather20°C (68°F)85 mm (3.4 inches)80%very high
October Weather12°C (55°F)131 mm (5.2 inches)82%high
November Weather4°C (39°F)57 mm (2.3 inches)88%moderate
December Weather1°C (33°F)54 mm (2.1 inches)84%low

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