May weather forecast and climate
Roy, MT

The last month of the spring, May, is a mild month in Roy, Montana, with temperature in the range of an average low of 40.1°F (4.5°C) and an average high of 58.5°F (14.7°C).

Temperature

In Roy, the average high-temperature in May rises, from a frosty 47.8°F (8.8°C) in April, to a moderate 58.5°F (14.7°C). The average low-temperature, in May, is 40.1°F (4.5°C).

Humidity

In May, the average relative humidity in Roy, Montana, is 65%.

Rainfall

May is the month with the most rainfall in Roy. Rain falls for 19.3 days and accumulates 3.39" (86mm) of precipitation.

Snowfall

January through June, September through December are months with snowfall. In Roy, snow falls for 2.4 days, with typically accumulated 2.48" (63mm) of snow. Throughout the year, there are 83.4 snowfall days, and 45.51" (1156mm) of snow is accumulated.

Daylight

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

Sunshine

In May, the average sunshine in Roy is 10h.

UV index

The average daily maximum UV index in Roy is 4. A UV Index value of 3 to 5 symbolizes a moderate threat to health from the exposure to the Sun's UV radiation for ordinary individuals.
Note: The average daily UV index of 4 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. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. 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 Roy?

The average high-temperature, in May, in Roy, Montana, is 58.5°F (14.7°C), while the average low-temperature is 40.1°F (4.5°C).

What is the average humidity in May in Roy?

The average relative humidity in May in Roy, Montana, is 65%.

How many days does it rain in May in Roy?

In Roy, in May, during 19.3 rainfall days, 3.39" (86mm) of precipitation is typically accumulated.

What is the wettest month in Roy?

May is the month with the most rainfall in Roy. Rain falls for 19.3 days and accumulates 3.39" (86mm) of precipitation.

How many days does it snow in May in Roy?

In Roy, in May, during 2.4 snowfall days, 2.48" (63mm) of snow is typically accumulated.

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

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

How many hours of sunshine does Roy have in May?

In Roy, the average sunshine in May is 10h.

What is the UV index intensity in May in Roy?

In Roy, Montana, the average daily maximum UV index in May is 4. A UV Index reading of 3 to 5 represents a medium hazard to health from unsafe exposure to the Sun's UV rays.
Average temperature in May - Roy, MT
  • Average high temperature in May: 14.7°C

The warmest month (with the highest average high temperature) is July (26°C).
Months with the lowest average high temperature are February and December (-1.6°C).

  • Average low temperature in May: 4.5°C

The month with the highest average low temperature is August (12.5°C).
The coldest month (with the lowest average low temperature) is February (-9.3°C).

Average pressure in May - Roy, MT
  • Average pressure in May: 1013.3mbar

The month with the highest atmospheric pressure is January (1020.3mbar).
The month with the lowest atmospheric pressure is June (1010.9mbar).

Average wind speed in May - Roy, MT
  • Average wind speed in May: 14.2km/h

The windiest months (with the highest average wind speed) are January, April and October (15.9km/h).
The calmest month (with the lowest average wind speed) is August (11.9km/h).

Average humidity in May - Roy, MT
  • Average humidity in May: 65%

The month with the highest relative humidity is February (79%).
The month with the lowest relative humidity is August (47%).

Average rainfall in May - Roy, MT
  • Average rainfall in May: 86mm

The wettest month (with the highest rainfall) is May (86mm).
The driest month (with the least rainfall) is December (18mm).

Average rainfall days in May - Roy, MT
  • Average rainfall days in May: 19.3 days

The month with the highest number of rainy days is May (19.3 days).
The month with the least rainy days is January (5.4 days).

Average snowfall in May - Roy, MT
  • Average snowfall in May: 63mm

The month with the highest snowfall is April (232mm).
Months with the least snowfall are July and August (0mm).

Average snowfall days in May - Roy, MT
  • Average snowfall days in May: 2.4 days

The month with the highest number of snowfall days is February (15.2 days).
Months with the least snowfall days are July and August (0 days).

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

The month with the longest days is June (Average daylight: 15.9h).
The month with the shortest days is December (Average daylight: 8.5h).

  • Average sunshine in May: 10h

The month with the most sunshine is July (Average sunshine: 11.8h).
The month with the least sunshine is February (Average sunshine: 5.5h).

Average sunshine days in May - Roy, MT
  • Average sunshine days in May: 8.9 days

The month with the most sunshine days is September (19.3 days).
The month with the least sunshine days is April (8.3 days).

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

The month with the highest UV index is July (UV index 6).
Months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).

Average cloud cover in May - Roy, MT
  • Average cloud cover in May: 36

The month with the most cloud cover is February (Cloud cover 45).
The month with the least cloud cover is July (Cloud cover 16).

Average visibility in May - Roy, MT
  • Average visibility in May: 9km

Months with the highest visibility are June, July, August and September (10km).
Months with the lowest visibility are January, February, March, April, May, October, November and December (9km).