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 commencement of December in O'Fallon involves a temperature shift, with the average high-temperature dropping from a cool 53.2°F (11.8°C) in November to a cold 41.9°F (5.5°C). An average low-temperature of 30.4°F (-0.9°C) is common during the nights of December.Humidity
In O'Fallon, the average relative humidity in December is 76%.Rainfall
The month with the least rainfall is December, when the rain falls for 7 days and typically collects 0.91" (23mm) of precipitation.Snowfall
January through March, November and December are months with snowfall. In O'Fallon, during December, snow falls for 3.9 days and regularly aggregates up to 0.67" (17mm) of snow. In O'Fallon, during the entire year, snow falls for 19 days and aggregates up to 4.13" (105mm) of snow.Daylight
With an average of 9h and 30min of daylight, December has the shortest days of the year in O'Fallon.On the first day of the month, sunrise is at 7:02 am and sunset at 4:41 pm. On the last day of December, sunrise is at 7:20 am and sunset at 4:51 pm CST.
Sunshine
In December, the average sunshine is 4.8h.UV index
The months with the lowest UV index in O'Fallon are January, February, November and December, with an average maximum UV index of 2. A UV Index reading of 2, and below, represents a low health risk from exposure to the Sun's UV rays for the average person.Note: During December, 2 as the daily maximum UV index converts into the following advice:
Despite most people tolerating extended sun exposure, it is critical to always protect those with sensitive skin, infants, and children. Avoiding direct sunlight during midday hours helps reduce the risk from intense UV radiation. A hat with a broad brim is indispensable, filtering out up to half of UV rays. Note well! The intensity of the Sun's UV rays can be nearly doubled by snow reflection.
Frequently asked questions
How cold is it in O'Fallon in December?
What is the average humidity in December in O'Fallon?
What is the driest month in O'Fallon?
How much does it rain in O'Fallon in December?
How much does it snow in O'Fallon in December?
What is the month with the shortest days in O'Fallon?
What is the average length of the day in December in O'Fallon?
What time are sunrise and sunset in December in O'Fallon?
How long on average sun shines in December in O'Fallon?
When is the lowest UV index in O'Fallon?
How high is the UV index in December in O'Fallon?
Average temperature in December
O'Fallon, MO
- Average high temperature in December: 41.9°F
The warmest month (with the highest average high temperature) is July (87.1°F).
The month with the lowest average high temperature is January (37.4°F).
- Average low temperature in December: 30.4°F
The month with the highest average low temperature is July (68.5°F).
The coldest month (with the lowest average low temperature) is January (23.7°F).
Average pressure in December
O'Fallon, MO
- Average pressure in December: 30.13"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
O'Fallon, MO
- Average wind speed in December: 8.6mph
The windiest month (with the highest average wind speed) is January (9.1mph).
The calmest month (with the lowest average wind speed) is July (5.5mph).
Average humidity in December
O'Fallon, MO
- Average humidity in December: 76%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (70%).
Average rainfall in December
O'Fallon, MO
- Average rainfall in December: 0.91"
The wettest month (with the highest rainfall) is May (2.76").
The driest month (with the least rainfall) is December (0.91").
Average rainfall days in December
O'Fallon, MO
- Average rainfall days in December: 7 days
The month with the highest number of rainy days is May (15.7 days).
The month with the least rainy days is February (6.8 days).
Average snowfall in December
O'Fallon, MO
- Average snowfall in December: 0.67"
The month with the highest snowfall is February (1.61").
The months with the least snowfall are April, May, June, July, August, September and October (0").
Average snowfall days in December
O'Fallon, MO
- Average snowfall days in December: 3.9 days
The months with the highest number of snowfall days are January and February (5.8 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).
Average daylight in December /
Average sunshine in December
O'Fallon, MO
- Average daylight in December: 9h and 3min
The month with the longest days is June (Average daylight: 14h and 48min).
The month with the shortest days is December (Average daylight: 9h and 30min).
- Average sunshine in December: 4h and 5min
The month with the most sunshine is June (Average sunshine: 10h and 30min).
The months with the least sunshine are January and February (Average sunshine: 4h and 42min).
Average sunshine days in December
O'Fallon, MO
- Average sunshine days in December: 20.6 days
The month with the most sunshine days is December (20.6 days).
The month with the least sunshine days is July (12.6 days).
Average UV index in December
O'Fallon, MO
- Average UV index in December: 2
The months with the highest UV index are May, June, July and August (UV index 6).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in December
O'Fallon, MO
- Average cloud cover in December: 47
The month with the most cloud cover is January (Cloud cover 50).
The months with the least cloud cover are June, July, August and September (Cloud cover 28).
Average visibility in December
O'Fallon, MO
- 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).
O'Fallon, Missouri, USA
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