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September Weather in Waukesha, United States

Last updated: June 24, 2025

In September, the average temperature in Waukesha, United States hovers around 19°C (66°F), with a minimum dip to 3°C (38°F) and a maximum rise to 34°C (93°F). Expect a total precipitation of 99 mm (3.9 in) spread across 9 days, and experience a comfortable average humidity of 79%.

September Temperature in Waukesha

In September in Waukesha, the average temperature is 19°C (66°F). Maximums can reach 34°C (93°F), while minimums can dip to as low as 3°C (38°F). This variability makes Waukesha a great destination for travelers who enjoy diverse weather experiences.

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

The chart illustrates September temperature patterns in Waukesha, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Waukesha, September typically has an average temperature of 19°C (66°F), with highs reaching up to 34°C (93°F) and lows dropping to around 3°C (38°F).
JanFebMarAprMayJunJulAugSepOctNovDec232536455869747265523730
Data source: Temperature data for Waukesha 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 Waukesha

In Waukesha in September, the precipitation amount is 99 mm (3.9 in) during a span of 9 days.

September Precipitation Trends in Waukesha

The chart displays monthly precipitation patterns in Waukesha, 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 Waukesha, September typically receives around 99 mm (3.9 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec5753621091341059282991114748
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Waukesha

In Waukesha in September humidity is 79%. With an average temperature of 19°C (66°F), this humidity feels like a warm embrace, making it feel much warmer than the actual temperature and creating a heavy, sticky atmosphere that can be a bit uncomfortable for traveling.

September Average Humidity in Waukesha

This chart illustrates the average monthly humidity levels in Waukesha, 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 Waukesha is approximately 79%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec85%85%85%85%78%80%78%76%79%83%88%82%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Waukesha

In Waukesha in September, the maximum UV index is 7, which corresponds to the high Exposure Category. This means that the time to burn is approximately 25 minutes. For more detailed information, you can check the Hourly UV Index in Waukesha.

Maximum UV Index Levels in Waukesha for September

The chart shows the monthly maximum UV Index (UVI) for Waukesha 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 Waukesha typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34589101097532
Data source: Waukesha 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 Waukesha Compares to Other Months

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

This table compares monthly weather conditions in Waukesha, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-5°C (23°F)57 mm (2.2 inches)85%moderate
February Weather-4°C (25°F)53 mm (2.1 inches)85%moderate
March Weather2°C (36°F)62 mm (2.5 inches)85%moderate
April Weather7°C (46°F)109 mm (4.3 inches)85%very high
May Weather14°C (58°F)134 mm (5.3 inches)78%very high
June Weather21°C (69°F)105 mm (4.1 inches)80%very high
July Weather23°C (75°F)92 mm (3.6 inches)78%very high
August Weather22°C (72°F)82 mm (3.2 inches)76%very high
September Weather19°C (66°F)99 mm (3.9 inches)79%high
October Weather11°C (52°F)111 mm (4.4 inches)83%moderate
November Weather3°C (38°F)47 mm (1.8 inches)88%moderate
December Weather-1°C (31°F)48 mm (1.9 inches)81%low

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