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

Weather in May

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

Temperature

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

Humidity

In Helena, Montana, the average relative humidity is 62%.

Rainfall

In Helena, Montana, during May, the rain falls for 15.8 days and regularly aggregates up to 1.5" (38mm) of precipitation. In Helena, during the entire year, the rain falls for 123.7 days and collects up to 12.4" (315mm) of precipitation.

Snowfall

Months with snowfall in Helena are January through May, September through December. 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. In Helena, during the entire year, snow falls for 80.4 days, and aggregates up to 34.88" (886mm) of snow.

Daylight

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

Sunshine

In Helena, the average sunshine is 10.3h.

UV index

In May, the average daily maximum UV index is 4. A UV Index reading of 3 to 5 represents a moderate health risk from unprotected exposure to the Sun's UV rays for average individuals.
Note: The average daily UV index of 4 in May transform into the following instructions:
Take precautions. Light skin individuals may get burned in less than 30 minutes. The solar radiation is most powerful near the mid-day, so the exposure to the direct Sun should be reduced accordingly. 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.
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FAQ

What is the temperature in May in Helena?

The average high-temperature, in May, in Helena, is 59.4°F (15.2°C), while the average low-temperature is 36.9°F (2.7°C).

What is the average humidity in May in Helena?

The average relative humidity in May is 62%.

How many days does it rain in May in Helena?

In May, in Helena, Montana, the rain falls for 15.8 days. Throughout May, 1.5" (38mm) of precipitation is accumulated.

What is the last month it snows in Helena?

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

How many hours of daylight does Helena have in May?

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

How long on average sun shines in May in Helena?

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

What is the UV index intensity in May in Helena?

In Helena, the average daily maximum UV index in May is 4. A UV Index estimate of 3 to 5 represents a moderate vulnerability from the exposure to the Sun's UV rays.

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"

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

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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%).
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").
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).
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: 15.1h

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

  • Average sunshine in May: 10.3h

The month with the most sunshine is July (Average sunshine: 11.7h).
The month with the least sunshine is January (Average sunshine: 5.6h).

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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).
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

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

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