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September Weather in Basalt, United States

Last updated: June 24, 2025

In September, the average temperature in Basalt, United States hovers around 11°C (52°F), with a minimum plunging to -7°C (19°F) and a pleasant maximum of 26°C (80°F). You'll experience a moderate precipitation of 35 mm (1.4 in) spread over 7 days, accompanied by an average humidity level of 65%. Prepare accordingly for a mix of chilly and warm days!

September Temperature in Basalt

In September in Basalt, the average temperature is 11°C (52°F), with maximums reaching up to 26°C (80°F) and minimums dropping as low as -7°C (19°F). When planning your trip, be prepared for a wide range of temperatures and pack accordingly to enjoy all that Basalt has to offer.

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

The chart illustrates September temperature patterns in Basalt, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Basalt, September typically has an average temperature of 11°C (52°F), with highs reaching up to 26°C (80°F) and lows dropping to around -7°C (19°F).
JanFebMarAprMayJunJulAugSepOctNovDec182028334053605952362417
Data source: Temperature data for Basalt generated using information from the Copernicus Climate Change Service.
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The average of daily temperatures (24 hours) calculated across all days in the month.

September Precipitation in Basalt

In Basalt in September, the precipitation amount is 35 mm (1.4 in) over the course of 7 days.

September Precipitation Trends in Basalt

The chart displays monthly precipitation patterns in Basalt, 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 Basalt, September typically receives around 35 mm (1.4 inches) of precipitation spread over approximately 7 days.
JanFebMarAprMayJunJulAugSepOctNovDec628185666132463035675369
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Basalt

In Basalt in September humidity is 65%. With average temperature 11°C (52°F) this humidity feels like a cool, damp blanket wrapping around you, making outdoor adventures invigorating yet slightly uncomfortable, as you'll need to layer up to stay warm and dry while exploring.

September Average Humidity in Basalt

This chart illustrates the average monthly humidity levels in Basalt, 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 Basalt is approximately 65%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec88%87%81%76%67%58%52%56%65%76%82%89%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Basalt

In Basalt in September, the maximum UV index reaches 10, which corresponds to a very high Exposure Category. With a time to burn of just 15 minutes, it's crucial to take precautions. For more detailed information, you can check the Hourly UV Index in Basalt.

Maximum UV Index Levels in Basalt for September

The chart shows the monthly maximum UV Index (UVI) for Basalt 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 Basalt typically reaches 10, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec469121314131210754
Data source: Basalt 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 Basalt Compares to Other Months

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

This table compares monthly weather conditions in Basalt, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-8°C (18°F)61 mm (2.4 inches)88%moderate
February Weather-7°C (20°F)81 mm (3.2 inches)87%high
March Weather-2°C (28°F)85 mm (3.3 inches)81%very high
April Weather0°C (33°F)66 mm (2.6 inches)76%extreme
May Weather4°C (40°F)61 mm (2.4 inches)66%extreme
June Weather12°C (53°F)32 mm (1.3 inches)58%extreme
July Weather16°C (60°F)46 mm (1.8 inches)52%extreme
August Weather15°C (59°F)30 mm (1.2 inches)56%extreme
September Weather11°C (52°F)35 mm (1.4 inches)65%very high
October Weather2°C (36°F)67 mm (2.6 inches)76%high
November Weather-4°C (24°F)53 mm (2.1 inches)82%moderate
December Weather-9°C (17°F)69 mm (2.7 inches)89%moderate

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