May weather forecast
Boulder, MT

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Weather in May

May, the last month of the spring in Boulder, is a moderate month, with an average temperature ranging between min 35.2°F (1.8°C) and max 58.5°F (14.7°C).

Temperature

The arrival of May brings a temperature shift, with the average high-temperature escalating from a chilly 46.4°F (8°C) in April to a refreshing 58.5°F (14.7°C). Boulder documents a significant temperature variance in May, with the mean nighttime lows settling at an icy 35.2°F (1.8°C).

Humidity

In Boulder, the average relative humidity in May is 64%.

Rainfall

In Boulder, in May, during 18.2 rainfall days, 2.36" (60mm) of precipitation is typically accumulated. In Boulder, Montana, during the entire year, the rain falls for 133.7 days and collects up to 16.38" (416mm) of precipitation.

Snowfall

January through June, September through December are months with snowfall. In Boulder, in May, during 4.4 snowfall days, 2.64" (67mm) of snow is typically accumulated. In Boulder, during the entire year, snow falls for 105.8 days and aggregates up to 55.12" (1400mm) of snow.

Daylight

The average length of the day in May in Boulder is 15h and 1min.
On the first day of May, sunrise is at 6:13 am and sunset at 8:37 pm. On the last day of the month, sunrise is at 5:40 am and sunset at 9:12 pm MDT.

Sunshine

In Boulder, Montana, the average sunshine in May is 10.2h.

UV index

In Boulder, Montana, the average daily maximum UV index in May is 4. A UV Index of 3 to 5 symbolizes a medium vulnerability from unprotected exposure to Sun's UV rays for ordinary individuals.
Note: The average daily UV index of 4 in May transforms into the following instructions:
Guard yourself - An obligation to protect skin and eyes from harm exists. UV radiation is strongest from the Sun during midday; protect yourself by staying in shaded areas. Safeguard your eyes, ears, and face from sun rays with the aid of a wide-brim hat. Bear in mind! The Sun's UV radiation can nearly double in intensity due to the reflective quality of snow.
Updated: Feb 13, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are May temperatures in Boulder?

Boulder in May has an average high-temperature of 58.5°F (14.7°C) and an average low-temperature of 35.2°F (1.8°C).

What is the average humidity in May in Boulder?

In Boulder, the average relative humidity in May is 64%.

How much does it rain in Boulder in May?

In Boulder, in May, it is raining for 18.2 days, with typically 2.36" (60mm) of accumulated precipitation.

How much does it snow in Boulder in May?

In Boulder, Montana, in May, snow falls for 4.4 days, with typically accumulated 2.64" (67mm) of snow.

How many hours of daylight does Boulder have in May?

The average day length in May in Boulder is 15h and 1min.

When is the sunrise / sunset in May in Boulder?

On the first day of May in Boulder, sunrise is at 6:13 am and sunset at 8:37 pm. On the last day of the month, sunrise is at 5:40 am and sunset at 9:12 pm MDT.

How many hours of sunshine does Boulder have in May?

In Boulder, the average sunshine duration in May is 10.2h.

How high is the UV index in May in Boulder?

The average daily maximum UV index in May in Boulder, Montana, is 4. A UV Index reading 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 daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in May
Boulder, MT

Average temperature in May - Boulder, MT
  • Average high temperature in May: 58.5°F

The warmest month (with the highest average high temperature) is July (79.7°F).
The month with the lowest average high temperature is December (27°F).

  • Average low temperature in May: 35.2°F

The month with the highest average low temperature is August (48.6°F).
The coldest month (with the lowest average low temperature) is December (12.6°F).

Average pressure in May
Boulder, MT

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

The month with the highest atmospheric pressure is January (30.19"Hg).
The month with the lowest atmospheric pressure is June (29.91"Hg).

Average wind speed in May
Boulder, MT

Average wind speed in May - Boulder, MT
  • Average wind speed in May: 5.4mph

The windiest months (with the highest average wind speed) are January and November (6.5mph).
The calmest month (with the lowest average wind speed) is August (4.7mph).

Average humidity in May
Boulder, MT

Average humidity in May - Boulder, MT
  • Average humidity in May: 64%

The month with the highest relative humidity is January (86%).
The month with the lowest relative humidity is August (46%).

Average rainfall in May
Boulder, MT

Average rainfall in May - Boulder, MT
  • Average rainfall in May: 2.36"

The wettest month (with the highest rainfall) is June (2.68").
The driest month (with the least rainfall) is December (0.79").

Average rainfall days in May
Boulder, MT

Average rainfall days in May - Boulder, MT
  • Average rainfall days in May: 18.2 days

The month with the highest number of rainy days is May (18.2 days).
The month with the least rainy days is November (7.5 days).

Average snowfall in May
Boulder, MT

Average snowfall in May - Boulder, MT
  • Average snowfall in May: 2.64"

The month with the highest snowfall is February (9.72").
The months with the least snowfall are July and August (0").

Average snowfall days in May
Boulder, MT

Average snowfall days in May - Boulder, MT
  • Average snowfall days in May: 4.4 days

The month with the highest number of snowfall days is February (18 days).
The months with the least snowfall days are July and August (0 days).

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

Average daylight in May / Average sunshine in May - Boulder, MT
  • Average daylight in May: 15h and 0min

The month with the longest days is June (Average daylight: 15h and 42min).
The month with the shortest days is December (Average daylight: 8h and 42min).

  • Average sunshine in May: 10h and 1min

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

Average sunshine days in May
Boulder, MT

Average sunshine days in May - Boulder, MT
  • Average sunshine days in May: 9.3 days

The month with the most sunshine days is September (17.9 days).
The month with the least sunshine days is February (8.5 days).

Average UV index in May
Boulder, MT

Average UV index in May - Boulder, 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).

Average cloud cover in May
Boulder, MT

Average cloud cover in May - Boulder, MT
  • Average cloud cover in May: 34

The month with the most cloud cover is February (Cloud cover 48).
The month with the least cloud cover is August (Cloud cover 15).

Average visibility in May
Boulder, MT

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

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

Boulder, Montana, USA

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