September Weather in Onalaska, United States

Last updated: June 24, 2025

In September, the average temperature in Onalaska, United States hovers around 18°C (64°F). Expect a minimum of 3°C (38°F) and a maximum reaching 33°C (92°F). During this month, precipitation totals approximately 109 mm (4.3 in) over about 10 days, with an average humidity level of 74%. Keep these factors in mind to make the most of your visit!

September Temperature in Onalaska

In September in Onalaska, the average temperature is 18°C (64°F). The maximum can reach 33°C (92°F), and the minimum can be as low as 3°C (38°F). This is a great time to pack both light clothing for the warm afternoons and a warmer layer for the cooler evenings while enjoying your travels.

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 18°C (64°F), with highs reaching up to 33°C (92°F) and lows dropping to around 3°C (38°F).

Data source: Temperature data for Onalaska generated using information from the Copernicus Climate Change Service.

September Precipitation in Onalaska

In Onalaska in September, the precipitation amount is 109 mm (4.3 in) spread over 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 109 mm (4.3 inches) of precipitation spread over approximately 10 days.

Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

September Humidity in Onalaska

In Onalaska in September humidity is 74%. With an average temperature of 18°C (64°F), this humidity feels like a warm embrace, making it ideal for leisurely strolls but potentially uncomfortable for extended outdoor activities.

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.

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.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	-7°C (19°F)	35 mm (1.4 inches)	84%	low
February Weather	-7°C (20°F)	49 mm (1.9 inches)	85%	moderate
March Weather	2°C (35°F)	57 mm (2.2 inches)	84%	moderate
April Weather	7°C (45°F)	86 mm (3.4 inches)	83%	very high
May Weather	15°C (59°F)	142 mm (5.6 inches)	75%	very high
June Weather	21°C (71°F)	139 mm (5.5 inches)	79%	very high
July Weather	23°C (74°F)	101 mm (4.0 inches)	75%	very high
August Weather	21°C (70°F)	127 mm (5.0 inches)	69%	very high
September Weather	18°C (64°F)	109 mm (4.3 inches)	74%	high
October Weather	10°C (50°F)	118 mm (4.6 inches)	79%	moderate
November Weather	2°C (35°F)	53 mm (2.1 inches)	88%	moderate
December Weather	-3°C (26°F)	44 mm (1.7 inches)	82%	low