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May Weather in Helena, United States

Last updated: June 24, 2025

In May, the average temperature in Helena, United States hovers around 9°C (48°F). Temperatures can vary significantly, with a minimum of -6°C (22°F) and a maximum reaching up to 26°C (79°F). Visitors should prepare for some rain, as there’s an average precipitation of 88 mm (3.5 in) spread over 15 days, and expect a comfortable average humidity of 76%.

May Temperature in Helena

In May in Helena, the average temperature is 9°C (48°F). Maximum temperatures can reach 26°C (79°F), while minimums can drop as low as -6°C (22°F). Be prepared for a wide range of weather conditions while exploring Helena this month!

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

The chart illustrates May 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, May typically has an average temperature of 9°C (48°F), with highs reaching up to 26°C (79°F) and lows dropping to around -6°C (22°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.

May Precipitation in Helena

In Helena in May, the precipitation amount is 88 mm (3.5 in) over a span of 15 days.

May Precipitation Trends in Helena

The chart displays monthly precipitation patterns in Helena, with values for each month alongside May’s data, which is highlighted for easy comparison. It shows the amount of precipitation, providing insights into how May’s conditions compare to those of other months. In Helena, May typically receives around 88 mm (3.5 inches) of precipitation spread over approximately 15 days.
JanFebMarAprMayJunJulAugSepOctNovDec2351386788107313444413333
Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.
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May Humidity in Helena

In Helena in May humidity is 76%. With an average temperature of 9°C (48°F), this humidity feels like a chilly embrace, making outdoor activities feel damp and brisk, potentially leaving you feeling colder than the temperature suggests.

May Average Humidity in Helena

This chart illustrates the average monthly humidity levels in Helena, with May’s data highlighted for easy comparison. It shows the fluctuation in humidity throughout the year, helping you understand how conditions vary by season. In May, average humidity in Helena is approximately 76%, 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 May generated using information from the Copernicus Climate Change Service.

May UV Index in Helena

In Helena in May, 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 May

The chart shows the monthly maximum UV Index (UVI) for Helena in May, 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 May, the maximum UV index in Helena typically reaches 9, which falls under the very high exposure category.
JanFebMarAprMayJunJulAugSepOctNovDec34689111098532
Data source: Helena May 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 May 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 May’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 May’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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