September Weather in Willow, United States

Last updated: June 24, 2025

In Willow, United States, the average temperature in September hovers around 9°C (49°F). Expect a chill, as minimum temperatures can drop to -6°C (21°F), while a mild day can reach up to 21°C (70°F). With 107 mm (4.2 in) of precipitation spread over 17 days, you'll want to pack an umbrella! Don't forget, the average humidity is a high 97%, adding to the overall damp feel of the month.

September Temperature in Willow

In September in Willow, the average temperature is 9°C (49°F). The maximum can reach 21°C (70°F), and the minimum can be as low as -6°C (21°F). It's advisable to pack layers to accommodate the fluctuating temperatures during your travels.

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

The chart illustrates September temperature patterns in Willow, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Willow, September typically has an average temperature of 9°C (49°F), with highs reaching up to 21°C (70°F) and lows dropping to around -6°C (21°F).

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

September Precipitation in Willow

In Willow in September, the precipitation amount is 107 mm (4.2 in) and occurs over 17 days.

September Precipitation Trends in Willow

The chart displays monthly precipitation patterns in Willow, 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 Willow, September typically receives around 107 mm (4.2 inches) of precipitation spread over approximately 17 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 Willow

In Willow in September, humidity is 97%. With an average temperature of 9°C (49°F), this humidity feels like a damp chill that clings to your skin, making even the simplest of outdoor activities feel laborious and uncomfortable for traveling.

September Average Humidity in Willow

This chart illustrates the average monthly humidity levels in Willow, 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 Willow is approximately 97%, 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 Willow

In Willow in September, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Willow for better planning.

Maximum UV Index Levels in Willow for September

The chart shows the monthly maximum UV Index (UVI) for Willow 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 Willow typically reaches 4, which falls under the moderate exposure category.

Data source: Willow 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 Willow Compares to Other Months

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

This table compares monthly weather conditions in Willow, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-12°C (10°F)	36 mm (1.4 inches)	95%	low
February Weather	-9°C (16°F)	48 mm (1.9 inches)	95%	low
March Weather	-6°C (22°F)	41 mm (1.6 inches)	90%	moderate
April Weather	2°C (36°F)	40 mm (1.6 inches)	82%	moderate
May Weather	9°C (49°F)	79 mm (3.1 inches)	85%	moderate
June Weather	14°C (57°F)	80 mm (3.2 inches)	95%	high
July Weather	16°C (62°F)	86 mm (3.4 inches)	100%	high
August Weather	14°C (58°F)	134 mm (5.3 inches)	99%	moderate
September Weather	9°C (49°F)	107 mm (4.2 inches)	97%	moderate
October Weather	3°C (37°F)	110 mm (4.3 inches)	93%	low
November Weather	-6°C (21°F)	67 mm (2.6 inches)	97%	low
December Weather	-8°C (17°F)	74 mm (2.9 inches)	98%	low