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September Weather in Prospect Heights, United States

Last updated: June 24, 2025

In September, the average temperature in Prospect Heights, United States hovers around 20°C (68°F). You can expect variations with a minimum of 3°C (38°F) and a maximum of 33°C (93°F). During this time, precipitation totals approximately 85 mm (3.3 in) over 9 days, contributing to an average humidity level of 80%.

September Temperature in Prospect Heights

In September in Prospect Heights, the average temperature is 20°C (68°F). Maximum temperatures can reach 33°C (93°F), while the minimum can drop to as low as 3°C (38°F). This variation makes Prospect Heights an ideal destination for travelers seeking diverse weather experiences.

September Weather in Prospect Heights: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Prospect Heights, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Prospect Heights, September typically has an average temperature of 20°C (68°F), with highs reaching up to 33°C (93°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec262839475971757367543933
Data source: Temperature data for Prospect Heights 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 Prospect Heights

In Prospect Heights in September, the precipitation amount is 85 mm (3.3 in) over the course of 9 days.

September Precipitation Trends in Prospect Heights

The chart displays monthly precipitation patterns in Prospect Heights, 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 Prospect Heights, September typically receives around 85 mm (3.3 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec61607911516413410592851275553
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Prospect Heights

In Prospect Heights 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 Prospect Heights

This chart illustrates the average monthly humidity levels in Prospect Heights, 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 Prospect Heights 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 Prospect Heights

In Prospect Heights 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 Prospect Heights.

Maximum UV Index Levels in Prospect Heights for September

The chart shows the monthly maximum UV Index (UVI) for Prospect Heights 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 Prospect Heights typically reaches 8, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689101098632
Data source: Prospect Heights 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 Prospect Heights Compares to Other Months

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

This table compares monthly weather conditions in Prospect Heights, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-4°C (26°F)61 mm (2.4 inches)82%moderate
February Weather-2°C (28°F)60 mm (2.4 inches)83%moderate
March Weather4°C (39°F)79 mm (3.1 inches)84%high
April Weather9°C (48°F)115 mm (4.5 inches)85%very high
May Weather15°C (60°F)164 mm (6.4 inches)79%very high
June Weather21°C (71°F)134 mm (5.3 inches)82%very high
July Weather24°C (75°F)105 mm (4.1 inches)80%very high
August Weather23°C (73°F)92 mm (3.6 inches)81%very high
September Weather20°C (68°F)85 mm (3.3 inches)80%very high
October Weather12°C (54°F)127 mm (5.0 inches)82%high
November Weather4°C (39°F)55 mm (2.2 inches)88%moderate
December Weather0°C (33°F)53 mm (2.1 inches)84%low

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