Helena
Montana, USA
Long-term weather forecast
Long-term weather forecast

May weather forecast and climate
Helena, MT

The State Capital building of Montana in Helena city, set on a beautiful natural park
The State Capital building of Montana in Helena city, set on a beautiful natural park
May, the last month of the spring, in Helena, is a comfortable month, with average temperature ranging between min 40.8°F (4.9°C) and max 67.1°F (19.5°C).

Temperature

In Helena, the average high-temperature increases, from a moderate 57.7°F (14.3°C) in April, to an enjoyable 67.1°F (19.5°C). In Helena, the average low-temperature is 40.8°F (4.9°C).

Humidity

The average relative humidity is 53.5%.

Rainfall

In Helena, in May, it is raining for 11.1 days, with typically 1.9" (47.5mm) of accumulated precipitation. In Helena, during the entire year, the rain falls for 91.6 days and collects up to 11.2" (284.9mm) of precipitation.

Snowfall

Months with snowfall are January through May, August through December. May is the last month it regularly snows in Helena. During 0.8 snowfall days, in May, Helena aggregates 0.9" (22.9mm) of snow. Throughout the year, in Helena, there are 32.8 snowfall days, and 38.1" (967.8mm) of snow is accumulated.

Daylight

The average length of the day in May is 15.1h.

Sunshine

In Helena, Montana, the average sunshine is 9.1h.

UV index

The average daily maximum UV index in May is 7. A UV Index of 6 to 7 symbolizes a high health hazard from unprotected exposure to the Sun's UV rays for ordinary individuals.
Note: In May, the average maximum UV index of 7 translate into the following recommendations:
Take precautions and utilize sun safety practices. Protection against the skin and eye damage is required. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. A wide-brim hat offers excellent sun protection for eyes, ears, face, and neck. Sunglasses with UVA and UVB protection significantly reduce eye damage from sun exposure. Tightly woven, loose-fitting clothes provide additional protection from the Sun. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.

What is the temperature in May in Helena?

In Helena, in May, the average high-temperature is 67.1°F (19.5°C), and the average low-temperature is 40.8°F (4.9°C).

What is the average humidity in May in Helena?

In May, the average relative humidity in Helena is 53.5%.

How much does it rain in Helena in May?

In Helena, Montana, in May, it is raining for 11.1 days, with typically 1.9" (47.5mm) of accumulated precipitation.

What is the last month it snows in Helena?

May is the last month it regularly snows in Helena. During 0.8 snowfall days, in May, Helena aggregates 0.9" (22.9mm) of snow.

How many hours of daylight does Helena have in May?

In Helena, Montana, the average length of the day in May is 15.1h.

How long on average sun shines in May in Helena?

In Helena, Montana, the average sunshine in May is 9.1h.

How high is the UV index in May in Helena?

In May, the average daily maximum UV index in Helena, Montana, is 7. A UV Index reading of 6 to 7 represents a high hazard to health from unsafe exposure to the Sun's UV rays.
Average temperature in May - Helena, MT
  • Average high temperature in May: 67.1°F

The warmest month (with the highest average high temperature) is July (85.7°F).
The month with the lowest average high temperature is December (31.7°F).

  • Average low temperature in May: 40.8°F

The month with the highest average low temperature is July (54.3°F).
The coldest month (with the lowest average low temperature) is December (11.9°F).

Average humidity in May - Helena, MT
  • Average humidity in May: 53.5%

The month with the highest relative humidity is December (68.1%).
The month with the lowest relative humidity is July (46.4%).

Average rainfall in May - Helena, MT
  • Average rainfall in May: 1.9"

The wettest month (with the highest rainfall) is June (2.1").
The driest month (with the lowest rainfall) is February (0.3").

Average rainfall days in May - Helena, MT
  • Average rainfall days in May: 11.1 days

The month with the highest number of rainy days is June (11.2 days).
The month with the lowest number of rainy days is February (5.9 days).

Average snowfall in May - Helena, MT
  • Average snowfall in May: 0.9"

The month with the highest snowfall is December (7.3").
Months with the lowest snowfall are June and July (0").

Average snowfall days in May - Helena, MT
  • Average snowfall days in May: 0.8 days

The month with the highest number of snowfall days is December (6 days).
The month with the lowest number of snowfall days is July (0 days).

Average daylight in May / Average sunshine in May - Helena, MT
  • Average daylight in May: 15.1h

The month with the longest days is June (Average daylight: 15.8h).
The month with shortest days is December (Average daylight: 8.6h).

  • Average sunshine in May: 9.1h

The month with most sunshine is July (Average sunshine: 11.9h).
The month with least sunshine is December (Average sunshine: 3.2h).

Average UV index in May - Helena, MT
  • Average UV index in May: 7

The month with the highest UV index is July (UV index 9).
Months with the lowest UV index are January, November and December (UV index 1).