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August Weather in Helena, United States

Last updated: June 24, 2025

In August, the average temperature in Helena, United States is a pleasant 18°C (65°F), with temperatures ranging from a chilly 3°C (39°F) to a warm 35°C (94°F). Expect a precipitation amount of about 34 mm (1.3 in) over approximately 6 days, and enjoy the comfortable average humidity of 71%.

August Temperature in Helena

In August in Helena, the average temperature is 18°C (65°F). The maximum can reach 35°C (94°F), and the minimum can be as low as 3°C (39°F). It’s advisable to pack both light clothing for warm days and warmer layers for cooler evenings during your travels.

August Weather in Helena: Daily Temperature Highs, Lows, and Averages

The chart illustrates August temperature patterns in Helena, showcasing daily minimum, maximum, and average temperatures. It highlights the typical range of temperatures throughout the month, providing insights into weather trends. In Helena, August typically has an average temperature of 18°C (65°F), with highs reaching up to 35°C (94°F) and lows dropping to around 3°C (39°F).
JanFebMarAprMayJunJulAugSepOctNovDec191629364858666555393021
Data source: Temperature data for Helena 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.

August Precipitation in Helena

In Helena in August, the total precipitation amount is 34 mm (1.3 in) spread over 6 days.

August Precipitation Trends in Helena

The chart displays monthly precipitation patterns in Helena, with values for each month alongside August’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how August’s conditions compare to those of other months. In Helena, August typically receives around 34 mm (1.3 inches) of precipitation spread over approximately 6 days.
JanFebMarAprMayJunJulAugSepOctNovDec2351386788107313444413333
Data source: Precipitation data for August generated using information from the Copernicus Climate Change Service.
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August Humidity in Helena

In Helena in August humidity is 71%. With an average temperature of 18°C (65°F), this humidity feels like a warm embrace, making it a bit sticky and muggy, which can be slightly uncomfortable for traveling, especially if you're engaging in outdoor activities or exploring the city on foot.

August Average Humidity in Helena

This chart illustrates the average monthly humidity levels in Helena, with August’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In August, average humidity in Helena is approximately 71%, offering insight into how humid the weather typically is during this month.
JanFebMarAprMayJunJulAugSepOctNovDec87%88%83%78%76%78%77%71%68%72%84%91%
Data source: Humidity data for August generated using information from the Copernicus Climate Change Service.

August UV Index in Helena

In Helena in August, 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 Helena.

Maximum UV Index Levels in Helena for August

The chart shows the monthly maximum UV Index (UVI) for Helena in August, 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 August, the maximum UV index in Helena typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689111098532
Data source: Helena August 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 August Weather in Helena Compares to Other Months

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

This table compares monthly weather conditions in Helena, showing how August’s temperature, precipitation, humidity, and UV index levels differ from those of other months.
 TemperaturePrecipitationHumidityUV
January Weather-7°C (20°F)23 mm (0.9 inches)87%moderate
February Weather-9°C (16°F)51 mm (2.0 inches)88%moderate
March Weather-2°C (29°F)38 mm (1.5 inches)83%high
April Weather2°C (36°F)67 mm (2.7 inches)78%very high
May Weather9°C (48°F)88 mm (3.5 inches)76%very high
June Weather14°C (58°F)107 mm (4.2 inches)78%extreme
July Weather19°C (67°F)31 mm (1.2 inches)77%very high
August Weather18°C (65°F)34 mm (1.3 inches)71%very high
September Weather13°C (55°F)44 mm (1.7 inches)68%very high
October Weather4°C (40°F)41 mm (1.6 inches)72%moderate
November Weather-1°C (30°F)33 mm (1.3 inches)84%moderate
December Weather-6°C (21°F)33 mm (1.3 inches)90%low

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