Contents
- Weather in December
- Frequently asked questions
- Average temperature in December
- Average pressure in December
- Average wind speed in December
- Average humidity in December
- Average rainfall in December
- Average rainfall days in December
- Average snowfall in December
- Average snowfall days in December
- Average daylight in December
- Average sunshine in December
- Average sunshine days in December
- Average UV index in December
- Average cloud cover in December
- Average visibility in December
Weather in December
Temperature
In Roy, Montana, the coldest months are February and December, registering an average high-temperature of 29.1°F (-1.6°C).Humidity
In December, the average relative humidity in Roy is 77%.Rainfall
December is the month with the least rainfall. Rain falls for 6 days and accumulates 0.71" (18mm) of precipitation.Snowfall
January through June, September through December are months with snowfall in Roy, Montana. In Roy, in December, snow falls for 13.5 days, with typically accumulated 4.88" (124mm) of snow. In Roy, during the entire year, snow falls for 83.4 days and aggregates up to 45.51" (1156mm) of snow.Daylight
December has the shortest days of the year in Roy, with an average of 8h and 30min of daylight.On the first day of December, sunrise is at 7:42 am and sunset at 4:27 pm. On the last day of the month, sunrise is at 8:02 am and sunset at 4:35 pm MST.
Sunshine
The average sunshine in December is 5.6h.UV index
The months with the lowest UV index in Roy are January through April, October through December, with an average maximum UV index of 2. A UV Index of 2, and less, symbolizes a low threat to health from exposure to the Sun's UV rays for the average person.Note: A maximum high daily UV index of 2 during December translates into the following directions:
Prolonged sun exposure should always be prevented in babies, children, and those with sensitive skin. The Sun's UV radiation is especially harmful around midday, so reduce exposure and stay safe. Clothes that are both tight-knit and comfortably loose are prime choices for sun protection. Mark this! Snow reflection can nearly double the UV radiation intensity from the Sun.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the coldest time of year in Roy?
How cold is it in Roy in December?
What is the average humidity in December in Roy?
What is the driest month in Roy?
How many days does it rain in December in Roy?
How much does it snow in Roy in December?
What is the month with the shortest days in Roy?
What is the average length of the day in December in Roy?
What time are sunrise and sunset in December in Roy?
How long on average sun shines in December in Roy?
What are the months with the lowest UV index in Roy?
What is the UV index intensity in December in Roy?
Average temperature in December
Roy, MT
- Average high temperature in December: 29.1°F
The warmest month (with the highest average high temperature) is July (78.8°F).
The months with the lowest average high temperature are February and December (29.1°F).
- Average low temperature in December: 16°F
The month with the highest average low temperature is August (54.5°F).
The coldest month (with the lowest average low temperature) is February (15.3°F).
Average pressure in December
Roy, MT
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.85"Hg).
Average wind speed in December
Roy, MT
- Average wind speed in December: 9.5mph
The windiest months (with the highest average wind speed) are January, April and October (9.9mph).
The calmest month (with the lowest average wind speed) is August (7.4mph).
Average humidity in December
Roy, MT
- Average humidity in December: 77%
The month with the highest relative humidity is February (79%).
The month with the lowest relative humidity is August (47%).
Average rainfall in December
Roy, MT
- Average rainfall in December: 0.71"
The wettest month (with the highest rainfall) is May (3.39").
The driest month (with the least rainfall) is December (0.71").
Average rainfall days in December
Roy, MT
- Average rainfall days in December: 6 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 December
Roy, MT
- Average snowfall in December: 4.88"
The month with the highest snowfall is April (9.13").
The months with the least snowfall are July and August (0").
Average snowfall days in December
Roy, MT
- Average snowfall days in December: 13.5 days
The month with the highest number of snowfall days is February (15.2 days).
The months with the least snowfall days are July and August (0 days).
Average daylight in December /
Average sunshine in December
Roy, MT
- Average daylight in December: 8h and 3min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in December: 5h and 4min
The month with the most sunshine is July (Average sunshine: 11h and 48min).
The month with the least sunshine is February (Average sunshine: 5h and 30min).
Average sunshine days in December
Roy, MT
- Average sunshine days in December: 16 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 December
Roy, MT
- Average UV index in December: 2
The month with the highest UV index is July (UV index 6).
The months with the lowest UV index are January, February, March, April, October, November and December (UV index 2).
Average cloud cover in December
Roy, MT
- Average cloud cover in December: 41
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 December
Roy, MT
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
Roy, Montana, USA
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