September Weather in Thief River Falls, United States

Last updated: June 24, 2025

In Thief River Falls, United States, the average temperature in September hovers around 15°C (59°F). Expect a range of -3°C (26°F) to 31°C (88°F), making it a month of diverse weather. With an average humidity of 77%, and precipitation totaling 84 mm (3.3 in) over approximately 10 days, it's wise to be prepared for both sunny and rainy spells!

September Temperature in Thief River Falls

In September in Thief River Falls, the average temperature is 15°C (59°F). Maximums can reach 31°C (88°F), and minimums can dip as low as -3°C (26°F). Travelers should be prepared for a wide range of temperatures, so layering clothing is advisable.

September Weather in Thief River Falls: Daily Temperature Highs, Lows, and Averages

The chart illustrates September temperature patterns in Thief River Falls, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Thief River Falls, September typically has an average temperature of 15°C (59°F), with highs reaching up to 31°C (88°F) and lows dropping to around -3°C (26°F).

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

September Precipitation in Thief River Falls

In Thief River Falls in September, the precipitation amount is 84 mm (3.3 in) over a span of 10 days.

September Precipitation Trends in Thief River Falls

The chart displays monthly precipitation patterns in Thief River Falls, 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 Thief River Falls, September typically receives around 84 mm (3.3 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 Thief River Falls

In Thief River Falls in September, humidity is 77%. With an average temperature of 15°C (59°F), this humidity feels like a warm blanket enveloping you, making it essential to stay hydrated and choose light, breathable clothing for comfortable travel.

September Average Humidity in Thief River Falls

This chart illustrates the average monthly humidity levels in Thief River Falls, 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 Thief River Falls is approximately 77%, 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 Thief River Falls

In Thief River Falls 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 Thief River Falls.

Maximum UV Index Levels in Thief River Falls for September

The chart shows the monthly maximum UV Index (UVI) for Thief River Falls 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 Thief River Falls typically reaches 7, which falls under the high exposure category.

Data source: Thief River Falls 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 Thief River Falls Compares to Other Months

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

This table compares monthly weather conditions in Thief River Falls, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
	Temperature	Precipitation	Humidity	UV
January Weather	-13°C (9°F)	19 mm (0.8 inches)	90%	low
February Weather	-14°C (8°F)	22 mm (0.9 inches)	92%	moderate
March Weather	-3°C (27°F)	26 mm (1.0 inches)	85%	moderate
April Weather	3°C (39°F)	43 mm (1.7 inches)	81%	high
May Weather	13°C (55°F)	54 mm (2.1 inches)	75%	very high
June Weather	20°C (68°F)	93 mm (3.7 inches)	79%	very high
July Weather	22°C (71°F)	62 mm (2.4 inches)	76%	very high
August Weather	20°C (68°F)	69 mm (2.7 inches)	78%	very high
September Weather	15°C (59°F)	84 mm (3.3 inches)	77%	high
October Weather	6°C (43°F)	81 mm (3.2 inches)	79%	moderate
November Weather	-3°C (26°F)	29 mm (1.1 inches)	86%	low
December Weather	-9°C (16°F)	38 mm (1.5 inches)	86%	low