May Weather in Helena, United States

Last updated: June 24, 2025

In Helena, United States, the average temperature in May is a pleasant 23°C (73°F). However, temperatures can vary significantly, with a minimum of 8°C (47°F) and a maximum of 34°C (93°F). Expect a precipitation amount of 138 mm (5.5 in) spread over approximately 12 days, and enjoy the humidity levels averaging around 83%.

May Temperature in Helena

In May in Helena, the average temperature is 23°C (73°F). The maximum can reach 34°C (93°F), while the minimum can drop as low as 8°C (47°F). This makes Helena an ideal destination for travelers seeking mild to warm weather during this time of year.

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 23°C (73°F), with highs reaching up to 34°C (93°F) and lows dropping to around 8°C (47°F).

Data source: Temperature data for Helena generated using information from the Copernicus Climate Change Service.

May Precipitation in Helena

In Helena in May, the precipitation amount is 138 mm (5.5 in) spread over a duration of 12 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 138 mm (5.5 inches) of precipitation spread over approximately 12 days.

Data source: Precipitation data for May generated using information from the Copernicus Climate Change Service.

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Millimeters (mm) Inches (in)

May Humidity in Helena

In Helena in May, humidity is 83%. With an average temperature of 23°C (73°F), this humidity feels like a heavy blanket wrapping around you, making travel slightly uncomfortable and causing you to break a sweat as you explore.

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 83%, offering insight into how humid the weather typically is during this month.

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 reaches 11, which corresponds to an extreme Exposure Category. With a time to burn of just 10 minutes, it's essential to take precautions. For more details, 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 11, which falls under the extreme exposure category.

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.
	Temperature	Precipitation	Humidity	UV
January Weather	7°C (44°F)	107 mm (4.2 inches)	84%	moderate
February Weather	9°C (48°F)	185 mm (7.3 inches)	83%	high
March Weather	14°C (57°F)	172 mm (6.8 inches)	81%	very high
April Weather	17°C (62°F)	146 mm (5.7 inches)	81%	very high
May Weather	23°C (73°F)	138 mm (5.5 inches)	83%	extreme
June Weather	26°C (79°F)	133 mm (5.2 inches)	83%	extreme
July Weather	28°C (82°F)	124 mm (4.9 inches)	81%	extreme
August Weather	27°C (81°F)	114 mm (4.5 inches)	74%	very high
September Weather	25°C (77°F)	92 mm (3.6 inches)	71%	very high
October Weather	19°C (66°F)	111 mm (4.4 inches)	76%	high
November Weather	11°C (52°F)	82 mm (3.2 inches)	84%	high
December Weather	9°C (49°F)	144 mm (5.7 inches)	88%	moderate