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
The onset of December comes with a shift in the average high-temperature, falling from a chilly 45.3°F (7.4°C) in November to a wintry 33.1°F (0.6°C). An average nighttime temperature of 22.3°F (-5.4°C) is observed during December.Humidity
In December, the average relative humidity is 81%.Rainfall
In December, in Mount Vernon, the rain falls for 6.8 days. Throughout December, 1.57" (40mm) of precipitation is accumulated. Throughout the year, there are 147.9 rainfall days, and 31.57" (802mm) of precipitation is accumulated.Snowfall
January through April, October through December are months with snowfall. In December, it is snowing for 9.5 days. Throughout December, 3.11" (79mm) of snow is accumulated. Throughout the year, there are 44 snowfall days, and 18.35" (466mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 12min of daylight.On the first day of December, sunrise is at 7:14 am and sunset at 4:35 pm. On the last day of the month, sunrise is at 7:33 am and sunset at 4:44 pm CST.
Sunshine
In December, the average sunshine is 4.3h.UV index
December is the month with the lowest UV index, with an average maximum UV index of 1. A UV Index reading of 2, and below, represents a low threat to health from exposure to the Sun's UV radiation for the average person.Note: A maximum UV index of 1 in December translates into the following recommendations:
Those with sensitive skin, infants, and children require constant safeguarding from prolonged sun exposure. Solar radiation is at its peak intensity during midday, so it's advisable to stay indoors or in the shade. Select sunglasses that boast both UVA and UVB protection to limit the adverse effects of the sun on the eyes. Observe! Snow reflection can nearly intensify the Sun's UV radiation twofold.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is December?
What is the average humidity in December?
How much does it rain in December?
How many days does it snow in December?
What is the month with the shortest days?
What is the average length of the day in December?
What time are sunrise and sunset in December?
How long on average sun shines in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Mount Vernon, IA
- Average high temperature in December: 33.1°F
The warmest month (with the highest average high temperature) is July (80.2°F).
The month with the lowest average high temperature is January (26.2°F).
- Average low temperature in December: 22.3°F
The month with the highest average low temperature is July (64.4°F).
The coldest month (with the lowest average low temperature) is January (14.2°F).
Average pressure in December
Mount Vernon, IA
- Average pressure in December: 30.11"Hg
The month with the highest atmospheric pressure is January (30.14"Hg).
The month with the lowest atmospheric pressure is June (29.9"Hg).
Average wind speed in December
Mount Vernon, IA
- Average wind speed in December: 10mph
The windiest month (with the highest average wind speed) is April (10.8mph).
The calmest months (with the lowest average wind speed) are July and August (7mph).
Average humidity in December
Mount Vernon, IA
- Average humidity in December: 81%
The month with the highest relative humidity is January (85%).
The month with the lowest relative humidity is October (73%).
Average rainfall in December
Mount Vernon, IA
- Average rainfall in December: 1.57"
The wettest month (with the highest rainfall) is May (5").
The driest month (with the least rainfall) is January (1.34").
Average rainfall days in December
Mount Vernon, IA
- Average rainfall days in December: 6.8 days
The month with the highest number of rainy days is May (19 days).
The months with the least rainy days are January and February (5.2 days).
Average snowfall in December
Mount Vernon, IA
- Average snowfall in December: 3.11"
The month with the highest snowfall is January (5.79").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Mount Vernon, IA
- Average snowfall days in December: 9.5 days
The month with the highest number of snowfall days is January (12.7 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Mount Vernon, IA
- Average daylight in December: 9h and 1min
The month with the longest days is June (Average daylight: 15h and 12min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 4h and 2min
The months with the most sunshine are July and August (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 4h and 0min).
Average sunshine days in December
Mount Vernon, IA
- Average sunshine days in December: 16.8 days
The month with the most sunshine days is November (17 days).
The month with the least sunshine days is June (8.1 days).
Average UV index in December
Mount Vernon, IA
- Average UV index in December: 1
The month with the highest UV index is July (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in December
Mount Vernon, IA
- Average cloud cover in December: 55
The month with the most cloud cover is January (Cloud cover 58).
The months with the least cloud cover are August and September (Cloud cover 31).
Average visibility in December
Mount Vernon, IA
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, August, September, October, November and December (6mi).
The month with the lowest visibility is July (5mi).
Mount Vernon, Iowa, USA
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