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 start of December comes with a reduction in the average high-temperature, receding from a cool 53.6°F (12°C) in November to a chilly 43.5°F (6.4°C). Saint Johns records a consistent low-temperature of 31.1°F (-0.5°C) during December nights.Humidity
In December, the average relative humidity is 77%.Rainfall
In December, in Saint Johns, the rain falls for 8.2 days. Throughout December, 1.57" (40mm) of precipitation is accumulated. Throughout the year, there are 147.6 rainfall days, and 29.17" (741mm) of precipitation is accumulated.Snowfall
January through April, November and December are months with snowfall. In December, it is snowing for 3.7 days. Throughout December, 0.87" (22mm) of snow is accumulated. In Saint Johns, during the entire year, snow falls for 18 days and aggregates up to 4.53" (115mm) of snow.Daylight
The month with the shortest days is December, with an average of 9h and 36min of daylight.On the first day of the month, sunrise is at 6:54 am and sunset at 4:37 pm. On the last day of December, in Saint Johns, sunrise is at 7:12 am and sunset at 4:47 pm CST.
Sunshine
The average sunshine in December is 4.8h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index in Saint Johns. A UV Index reading of 2, and below, represents a low health risk from unsafe exposure to UV radiation for average individuals.Note: The UV index of 2 during December leads to these advisories:
Children, infants, and individuals with sensitive skin should be constantly protected from extended sun exposure. When the Sun's UV radiation is most intense during midday, it's best to find shade and limit exposure. For minimizing sun-related eye damage, always choose sunglasses with UVA and UVB coverage. On your guard! Snow's reflection can almost double the intensity of the Sun's UV radiation.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
How cold is it in December?
What is the average humidity in December?
How much does it rain in December?
How much does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Saint Johns have in December?
When are sunrise and sunset in December?
How long on average sun shines in December?
What are the months with the lowest UV index?
What is the UV index reading in December?
Average temperature in December
Saint Johns, IL
- Average high temperature in December: 43.5°F
The warmest month (with the highest average high temperature) is July (87.3°F).
The month with the lowest average high temperature is January (38.8°F).
- Average low temperature in December: 31.1°F
The month with the highest average low temperature is July (68.7°F).
The coldest month (with the lowest average low temperature) is January (25.7°F).
Average pressure in December
Saint Johns, IL
- Average pressure in December: 30.14"Hg
The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.93"Hg).
Average wind speed in December
Saint Johns, IL
- Average wind speed in December: 8.9mph
The windiest months (with the highest average wind speed) are January and February (9.6mph).
The calmest months (with the lowest average wind speed) are July and August (5.8mph).
Average humidity in December
Saint Johns, IL
- Average humidity in December: 77%
The month with the highest relative humidity is May (79%).
The month with the lowest relative humidity is October (71%).
Average rainfall in December
Saint Johns, IL
- Average rainfall in December: 1.57"
The wettest month (with the highest rainfall) is April (3.58").
The driest month (with the least rainfall) is January (1.5").
Average rainfall days in December
Saint Johns, IL
- Average rainfall days in December: 8.2 days
The month with the highest number of rainy days is May (17 days).
The month with the least rainy days is December (8.2 days).
Average snowfall in December
Saint Johns, IL
- Average snowfall in December: 0.87"
The month with the highest snowfall is February (1.5").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Saint Johns, IL
- Average snowfall days in December: 3.7 days
The month with the highest number of snowfall days is January (5.4 days).
The months with the least snowfall days are May, June, July, August and September (0 days).
Average daylight in December /
Average sunshine in December
Saint Johns, IL
- Average daylight in December: 9h and 4min
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 36min).
- Average sunshine in December: 4h and 5min
The month with the most sunshine is July (Average sunshine: 10h and 30min).
The month with the least sunshine is January (Average sunshine: 4h and 36min).
Average sunshine days in December
Saint Johns, IL
- Average sunshine days in December: 19.2 days
The months with the most sunshine days are October and November (19.5 days).
The month with the least sunshine days is May (11.4 days).
Average UV index in December
Saint Johns, IL
- Average UV index in December: 2
The months with the highest UV index are 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
Saint Johns, IL
- Average cloud cover in December: 49
The months with the most cloud cover are January and February (Cloud cover 50).
The month with the least cloud cover is June (Cloud cover 28).
Average visibility in December
Saint Johns, IL
- 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).
Saint Johns, Illinois, USA
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