May weather forecast
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

Weather in May

May, the last month of the spring in Helena, is a moderate month, with an average temperature varying between 36.9°F (2.7°C) and 59.4°F (15.2°C).

Temperature

In May, the average high-temperature increases from a frosty 47.8°F (8.8°C) in April to a mild 59.4°F (15.2°C). The average low-temperature, in Helena, is 36.9°F (2.7°C).

Humidity

The average relative humidity in May in Helena is 62%.

Rainfall

In Helena, Montana, during 15.8 rainfall days, 1.5" (38mm) of precipitation is typically accumulated. Throughout the year, in Helena, there are 123.7 rainfall days, and 12.4" (315mm) of precipitation is accumulated.

Snowfall

January through May, September through December are months with snowfall in Helena, Montana. May is the last month it regularly snows in Helena, Montana. During 1.3 snowfall days, Helena aggregates 0.67" (17mm) of snow. Throughout the year, there are 80.4 snowfall days, and 34.88" (886mm) of snow is accumulated.

Daylight

In Helena, the average length of the day in May is 15h and 2min.
On the first day of May, sunrise is at 6:12 am and sunset at 8:37 pm. On the last day of the month, sunrise is at 5:38 am and sunset at 9:12 pm MDT.

Sunshine

The average sunshine in May is 10.3h.

UV index

In May, the average daily maximum UV index in Helena is 4. A UV Index reading of 3 to 5 represents a moderate health risk from unsafe exposure to UV radiation for average individuals.
Note: In May, the average maximum UV index of 4 translate into the following recommendations:
Take precautions - Protection against sun damage is advised. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
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FAQ

What is the average humidity in May in Helena?

The average relative humidity in May in Helena is 62%.

How much does it rain in Helena in May?

In Helena, Montana, in May, it is raining for 15.8 days, with typically 1.5" (38mm) of accumulated precipitation.

What is the last month it snows in Helena?

May is the last month it regularly snows in Helena, Montana. During 1.3 snowfall days, in May, Helena aggregates 0.67" (17mm) of snow.

What is the average length of the day in May in Helena?

The average day length in May is 15h and 2min.

When is the sunrise / sunset in May in Helena?

In May, on the first day of the month, sunrise is at 6:12 am and sunset at 8:37 pm. On the last day of the month, sunrise is at 5:38 am and sunset at 9:12 pm MDT.

How many hours of sunshine does Helena have in May?

In May, the average sunshine duration in Helena is 10.3h.

What is the UV index intensity in May in Helena?

In May, the average daily maximum UV index is 4. A UV Index estimate of 3 to 5 represents a medium health risk from exposure to the Sun's UV radiation.
Average humidity
Average rainfall days
Average snowfall days
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in May
Helena, MT

Average temperature in May - Helena, MT
  • Average high temperature in May: 59.4°F

The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is December (27.7°F).

  • Average low temperature in May: 36.9°F

The month with the highest average low temperature is July (50.4°F).
The coldest month (with the lowest average low temperature) is December (14.2°F).

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Average pressure in May
Helena, MT

Average pressure in May - Helena, MT
  • Average pressure in May: 29.95"Hg

The month with the highest atmospheric pressure is January (30.18"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).

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Average wind speed in May
Helena, MT

Average wind speed in May - Helena, MT
  • Average wind speed in May: 5.8mph

The windiest month (with the highest average wind speed) is November (7.1mph).
The calmest month (with the lowest average wind speed) is August (5mph).

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Average humidity in May
Helena, MT

Average humidity in May - Helena, MT
  • Average humidity in May: 62%

The month with the highest relative humidity is January (85%).
The months with the lowest relative humidity are July and August (46%).

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Average rainfall in May
Helena, MT

Average rainfall in May - Helena, MT
  • Average rainfall in May: 1.5"

The wettest month (with the highest rainfall) is June (2.01").
The driest months (with the least rainfall) are January and December (0.63").

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Average rainfall days in May
Helena, MT

Average rainfall days in May - Helena, MT
  • Average rainfall days in May: 15.8 days

The month with the highest number of rainy days is May (15.8 days).
The month with the least rainy days is November (7 days).

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Average snowfall in May
Helena, MT

Average snowfall in May - Helena, MT
  • Average snowfall in May: 0.67"

The month with the highest snowfall is February (6.18").
The months with the least snowfall are June, July and August (0").

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Average snowfall days in May
Helena, MT

Average snowfall days in May - Helena, MT
  • Average snowfall days in May: 1.3 days

The month with the highest number of snowfall days is February (16.2 days).
The months with the least snowfall days are July and August (0 days).

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Average daylight in May /
Average sunshine in May
Helena, MT

Average daylight in May / Average sunshine in May - Helena, MT
  • Average daylight in May: 15h and 2min

The month with the longest days is June (Average daylight: 15h and 46min).
The month with the shortest days is December (Average daylight: 8h and 38min).

  • Average sunshine in May: 10h and 18min

The month with the most sunshine is July (Average sunshine: 11h and 42min).
The month with the least sunshine is January (Average sunshine: 5h and 36min).

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Average sunshine days in May
Helena, MT

Average sunshine days in May - Helena, MT
  • Average sunshine days in May: 12.2 days

The month with the most sunshine days is July (20.5 days).
The month with the least sunshine days is April (9.8 days).

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Average UV index in May
Helena, MT

Average UV index in May - Helena, MT
  • Average UV index in May: 4

The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is February (UV index 1).

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Average cloud cover in May
Helena, MT

Average cloud cover in May - Helena, MT
  • Average cloud cover in May: 33

The month with the most cloud cover is February (Cloud cover 47).
The months with the least cloud cover are July and August (Cloud cover 15).

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Average visibility in May
Helena, MT

Average visibility in May - Helena, MT
  • Average visibility in May: 6mi

The months with the highest visibility are March, April, May, June, July, August, September, October and November (6mi).
The months with the lowest visibility are January, February and December (5mi).

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