Last updated: June 24, 2025
In September, the average temperature in Butte, United States hovers around 11°C (53°F). However, be prepared for a wide range, with minimums dipping to -6°C (21°F) and maximums soaring to 31°C (88°F). During this month, precipitation averages 38 mm (1.5 in) over 6 days, contributing to a moderate humidity level of 66%.
In September in Butte, the average temperature is 11°C (53°F), with maximums reaching 31°C (88°F) and minimums dropping as low as -6°C (21°F). It's advisable to pack layers to prepare for the wide range of temperatures you'll encounter during your travels.
In Butte in September, the total precipitation amount is 38 mm (1.5 in) spread over 6 days.
In Butte in September humidity is 66%. With an average temperature of 11°C (53°F), this humidity feels like a cool, damp embrace that can make traveling slightly uncomfortable, as the moisture in the air clings to your skin and can leave you feeling chilled, especially during outdoor excursions.
In Butte in September, the maximum UV index is 8, which corresponds to a very high Exposure Category. This means that the time to burn is only 15 minutes. For more detailed information, you can refer to the Hourly UV Index in Butte.
UV Risk Categories
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.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -8°C (18°F) | 22 mm (0.9 inches) | 94% | moderate |
| February Weather | -9°C (17°F) | 58 mm (2.3 inches) | 93% | moderate |
| March Weather | -3°C (28°F) | 39 mm (1.5 inches) | 91% | high |
| April Weather | 1°C (33°F) | 63 mm (2.5 inches) | 87% | very high |
| May Weather | 7°C (45°F) | 89 mm (3.5 inches) | 83% | very high |
| June Weather | 13°C (55°F) | 94 mm (3.7 inches) | 80% | extreme |
| July Weather | 17°C (64°F) | 29 mm (1.1 inches) | 75% | very high |
| August Weather | 16°C (62°F) | 31 mm (1.2 inches) | 66% | very high |
| September Weather | 11°C (53°F) | 38 mm (1.5 inches) | 66% | very high |
| October Weather | 2°C (37°F) | 42 mm (1.7 inches) | 77% | moderate |
| November Weather | -3°C (27°F) | 34 mm (1.3 inches) | 91% | moderate |
| December Weather | -8°C (18°F) | 30 mm (1.2 inches) | 96% | low |