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September Weather in Challis, United States

Last updated: June 24, 2025

In September, the average temperature in Challis, United States hovers around 12°C (54°F). Expect a range that can dip as low as -6°C (21°F) and rise to a warm 31°C (88°F). During this month, you'll likely encounter about 30 mm (1.2 in) of precipitation over 6 days, with an average humidity of 66%. Stay prepared for a mix of conditions!

September Temperature in Challis

In September in Challis, the average temperature is 12°C (54°F). Maximum temperatures can reach up to 31°C (88°F), while minimum temperatures can drop as low as -6°C (21°F). Be prepared for a wide range of temperatures when traveling during this time.

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

The chart illustrates September temperature patterns in Challis, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Challis, September typically has an average temperature of 12°C (54°F), with highs reaching up to 31°C (88°F) and lows dropping to around -6°C (21°F).
JanFebMarAprMayJunJulAugSepOctNovDec151827324355656353372716
Data source: Temperature data for Challis 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 Challis

In Challis in September, the total precipitation amount is 30 mm (1.2 in) spread across 6 days.

September Precipitation Trends in Challis

The chart displays monthly precipitation patterns in Challis, 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 Challis, September typically receives around 30 mm (1.2 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec346541496859182330423438
Data source: Precipitation data for September generated using information from the Copernicus Climate Change Service.
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September Humidity in Challis

In Challis in September, humidity is 66%. With an average temperature of 12°C (54°F), this humidity feels like a cool embrace, making outdoor adventures comfortable yet slightly damp, perfect for exploring without the heat of summer weighing you down.

September Average Humidity in Challis

This chart illustrates the average monthly humidity levels in Challis, 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 Challis is approximately 66%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec94%93%91%87%83%80%75%66%66%77%92%96%
Data source: Humidity data for September generated using information from the Copernicus Climate Change Service.

September UV Index in Challis

In Challis in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Challis.

Maximum UV Index Levels in Challis for September

The chart shows the monthly maximum UV Index (UVI) for Challis 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 Challis typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec3589111111109642
Data source: Challis 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 Challis Compares to Other Months

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

This table compares monthly weather conditions in Challis, showing how September’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-9°C (16°F)34 mm (1.3 inches)94%moderate
February Weather-8°C (18°F)65 mm (2.6 inches)93%moderate
March Weather-3°C (27°F)40 mm (1.6 inches)91%very high
April Weather0°C (33°F)49 mm (1.9 inches)87%very high
May Weather6°C (44°F)68 mm (2.7 inches)83%extreme
June Weather13°C (55°F)59 mm (2.3 inches)80%extreme
July Weather18°C (65°F)18 mm (0.7 inches)75%extreme
August Weather17°C (63°F)23 mm (0.9 inches)66%very high
September Weather12°C (54°F)30 mm (1.2 inches)66%very high
October Weather3°C (37°F)42 mm (1.7 inches)77%high
November Weather-3°C (27°F)34 mm (1.3 inches)91%moderate
December Weather-9°C (16°F)38 mm (1.5 inches)96%low

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