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September Weather in West Allis, United States

Last updated: June 24, 2025

In West Allis, United States, the average temperature in September is a comfortable 19°C (66°F). However, be prepared for a range, as temperatures can dip to 5°C (42°F) and rise as high as 30°C (86°F). With 96 mm (3.8 in) of precipitation spread over 9 days, it's wise to carry an umbrella. The air remains humid, with an average humidity level of 79%, ensuring a true sense of the season.

September Temperature in West Allis

In September in West Allis, the average temperature is 19°C (66°F). Maximum can reach 30°C (86°F) and minimum can be as low as 5°C (42°F). This range of temperatures makes West Allis an ideal destination for travelers looking to enjoy mild weather while exploring.

September Weather in West Allis: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in West Allis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In West Allis, September typically has an average temperature of 19°C (66°F), with highs reaching up to 30°C (86°F) and lows dropping to around 5°C (42°F).
JanFebMarAprMayJunJulAugSepOctNovDec252635435465727165533832
Data source: Temperature data for West Allis 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 West Allis

In West Allis in September, the total precipitation amount is 96 mm (3.8 in) spread over a period of 9 days.

September Precipitation Trends in West Allis

The chart displays monthly precipitation patterns in West Allis, 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 West Allis, September typically receives around 96 mm (3.8 inches) of precipitation spread over approximately 9 days.
JanFebMarAprMayJunJulAugSepOctNovDec636068110138968275961215453
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in West Allis

In West Allis 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 West Allis

This chart illustrates the average monthly humidity levels in West Allis, 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 West Allis 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 West Allis

In West Allis 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 West Allis.

Maximum UV Index Levels in West Allis for September

The chart shows the monthly maximum UV Index (UVI) for West Allis 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 West Allis typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec24589101097532
Data source: West Allis 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 West Allis Compares to Other Months

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

This table compares monthly weather conditions in West Allis, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-4°C (25°F)63 mm (2.5 inches)85%low
February Weather-4°C (26°F)60 mm (2.4 inches)85%moderate
March Weather2°C (36°F)68 mm (2.7 inches)85%moderate
April Weather6°C (44°F)109 mm (4.3 inches)85%very high
May Weather12°C (54°F)138 mm (5.4 inches)78%very high
June Weather18°C (66°F)96 mm (3.8 inches)80%very high
July Weather22°C (72°F)82 mm (3.2 inches)78%very high
August Weather22°C (72°F)75 mm (2.9 inches)76%very high
September Weather19°C (66°F)96 mm (3.8 inches)79%high
October Weather12°C (53°F)121 mm (4.8 inches)83%moderate
November Weather3°C (39°F)54 mm (2.1 inches)88%moderate
December Weather0°C (32°F)53 mm (2.1 inches)81%low

Compare West Allis's Climate with Cities Worldwide