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September Weather in Onalaska, United States

Last updated: June 24, 2025

In Onalaska, United States, the average temperature in September hovers around 16°C (60°F). However, you can experience a range, with minimums dipping to 4°C (40°F) and maximums soaring to 33°C (91°F). Prepare for some moisture, as 86 mm (3.4 in) of precipitation is expected over about 10 days, accompanied by an average humidity of 74%.

September Temperature in Onalaska

In September in Onalaska, the average temperature is 16°C (60°F), with maximums reaching 33°C (91°F) and minimums dropping as low as 4°C (40°F). This diverse temperature range makes Onalaska an ideal destination for travelers seeking both warm and cooler experiences.

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

The chart illustrates September temperature patterns in Onalaska, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Onalaska, September typically has an average temperature of 16°C (60°F), with highs reaching up to 33°C (91°F) and lows dropping to around 4°C (40°F).
JanFebMarAprMayJunJulAugSepOctNovDec403944485560646660504440
Data source: Temperature data for Onalaska 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 Onalaska

In Onalaska in September, the precipitation amount is 86 mm (3.4 in) over the course of 10 days.

September Precipitation Trends in Onalaska

The chart displays monthly precipitation patterns in Onalaska, 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 Onalaska, September typically receives around 86 mm (3.4 inches) of precipitation spread over approximately 10 days.
JanFebMarAprMayJunJulAugSepOctNovDec1881961511298062121586149187202
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Onalaska

In Onalaska in September humidity is 74%. With an average temperature of 16°C (60°F), this humidity feels like a damp blanket enveloping you, making traveling a bit uncomfortable as you navigate the sticky air and potentially limiting your energy for exploring the sights.

September Average Humidity in Onalaska

This chart illustrates the average monthly humidity levels in Onalaska, 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 Onalaska is approximately 74%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec86%84%85%83%84%84%82%73%74%83%86%87%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Onalaska

In Onalaska 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 Onalaska.

Maximum UV Index Levels in Onalaska for September

The chart shows the monthly maximum UV Index (UVI) for Onalaska 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 Onalaska typically reaches 7, which falls under the high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec2356910987532
Data source: Onalaska 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 Onalaska Compares to Other Months

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

This table compares monthly weather conditions in Onalaska, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather5°C (41°F)188 mm (7.4 inches)86%low
February Weather4°C (39°F)196 mm (7.7 inches)84%moderate
March Weather6°C (44°F)151 mm (5.9 inches)85%moderate
April Weather9°C (49°F)129 mm (5.1 inches)83%high
May Weather13°C (55°F)80 mm (3.2 inches)84%very high
June Weather15°C (60°F)62 mm (2.4 inches)84%very high
July Weather18°C (65°F)12 mm (0.5 inches)82%very high
August Weather19°C (66°F)15 mm (0.6 inches)73%very high
September Weather16°C (60°F)86 mm (3.4 inches)74%high
October Weather10°C (50°F)149 mm (5.9 inches)83%moderate
November Weather7°C (44°F)187 mm (7.3 inches)86%moderate
December Weather4°C (40°F)202 mm (8.0 inches)87%low

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