September Weather in Butte, United States

Last updated: June 24, 2025

In Butte, United States, the average temperature in September hovers around 7°C (45°F), with extremes ranging from a brisk -8°C (17°F) to a mild 18°C (65°F). Expect 127 mm (5.0 in) of precipitation spread over 18 days, contributing to a high average humidity of 96%. Whether you're braving the chill or enjoying the occasional warm spell, make sure to prepare for a wet and damp month!

September Temperature in Butte

In September in Butte, the average temperature is 7°C (45°F), with maximums reaching 18°C (65°F) and minimums dropping as low as -8°C (17°F). Travelers should be prepared for a wide range of temperatures and varying weather conditions during this time.

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

The chart illustrates September temperature patterns in Butte, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Butte, September typically has an average temperature of 7°C (45°F), with highs reaching up to 18°C (65°F) and lows dropping to around -8°C (17°F).

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

September Precipitation in Butte

In Butte in September, the precipitation amount is 127 mm (5.0 in) spread over 18 days.

September Precipitation Trends in Butte

The chart displays monthly precipitation patterns in Butte, 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 Butte, September typically receives around 127 mm (5.0 inches) of precipitation spread over approximately 18 days.

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

Choose your preferred precipitation unit

Millimeters (mm) Inches (in)

September Humidity in Butte

In Butte in September humidity is 96%. With an average temperature of 7°C (45°F), this humidity feels like a heavy blanket embracing you, making traveling uncomfortable and sticky as the damp air clings to your skin, leaving little relief from the chill.

September Average Humidity in Butte

This chart illustrates the average monthly humidity levels in Butte, 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 Butte is approximately 96%, 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 Butte

In Butte 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 Butte for better planning.

Maximum UV Index Levels in Butte for September

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

Data source: Butte 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 Butte Compares to Other Months

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

This table compares monthly weather conditions in Butte, 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 (11°F)	80 mm (3.1 inches)	94%	low
February Weather	-10°C (15°F)	74 mm (2.9 inches)	93%	low
March Weather	-7°C (20°F)	72 mm (2.8 inches)	91%	moderate
April Weather	0°C (33°F)	54 mm (2.1 inches)	85%	moderate
May Weather	5°C (42°F)	75 mm (2.9 inches)	88%	high
June Weather	11°C (51°F)	83 mm (3.3 inches)	95%	high
July Weather	13°C (56°F)	89 mm (3.5 inches)	102%	high
August Weather	12°C (53°F)	137 mm (5.4 inches)	100%	moderate
September Weather	7°C (45°F)	127 mm (5.0 inches)	96%	moderate
October Weather	1°C (33°F)	173 mm (6.8 inches)	91%	low
November Weather	-9°C (17°F)	114 mm (4.5 inches)	95%	low
December Weather	-8°C (17°F)	142 mm (5.6 inches)	96%	low