December weather forecastPotomac, IL
December
Weather in December
December, the first month of the winter in Potomac, is still a cold month, with an average temperature fluctuating between 37.6°F (3.1°C) and 27.3°F (-2.6°C).Temperature
Transition into December marks a drop in the average high-temperature, moving from a chilly 48.4°F (9.1°C) in November to an icy 37.6°F (3.1°C). During the month of December, an average low-temperature of 27.3°F (-2.6°C) is recorded.Humidity
In Potomac, the average relative humidity in December is 81%.Rainfall
In Potomac, in December, it is raining for 8.5 days, with typically 1.26" (32mm) of accumulated precipitation. In Potomac, during the entire year, the rain falls for 146.3 days and collects up to 22.76" (578mm) of precipitation.Snowfall
Months with snowfall are January through April, November and December. In Potomac, Illinois, during December, snow falls for 8 days and regularly aggregates up to 1.57" (40mm) of snow. Throughout the year, in Potomac, there are 34.2 snowfall days, and 7.8" (198mm) of snow is accumulated.Daylight
December has the shortest days of the year, with an average of 9h and 24min of daylight.On the first day of December, sunrise is at 6:55 am and sunset at 4:25 pm. On the last day of the month, sunrise is at 7:13 am and sunset at 4:35 pm CST.
Sunshine
In December, the average sunshine is 4.4h.UV index
The month with the lowest UV index in Potomac is December, with an average maximum UV index of 1. A UV Index value of 2, and less, symbolizes a low threat to health from unprotected exposure to Sun's UV rays for average individuals.Note: An average maximum UV index of 1 in December leads to these recommendations:
It is important to always shield children, babies, and individuals with sensitive skin from prolonged exposure to the sun. The most potent solar radiation is around mid-day, so one should minimize exposure to direct sunlight during this period. To mitigate harm from sun exposure, pick sunglasses offering UVA and UVB defense. Note this! The Sun's UV radiation can nearly be doubled by the reflection off snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Potomac, IL
- Average high temperature in December: 37.6°F
The warmest month (with the highest average high temperature) is July (81.1°F).
The month with the lowest average high temperature is January (31.5°F).
- Average low temperature in December: 27.3°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 (19.8°F).
Average pressure in December
Potomac, IL
- 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 (29.93"Hg).
Average wind speed in December
Potomac, IL
- Average wind speed in December: 9.8mph
The windiest month (with the highest average wind speed) is January (10.5mph).
The calmest months (with the lowest average wind speed) are July and August (6.3mph).
Average humidity in December
Potomac, IL
- Average humidity in December: 81%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (72%).
Average rainfall in December
Potomac, IL
- Average rainfall in December: 1.26"
The wettest month (with the highest rainfall) is May (2.76").
The driest month (with the least rainfall) is February (1.18").
Average rainfall days in December
Potomac, IL
- Average rainfall days in December: 8.5 days
The month with the highest number of rainy days is July (17.7 days).
The month with the least rainy days is February (6.7 days).
Average snowfall in December
Potomac, IL
- Average snowfall in December: 1.57"
The month with the highest snowfall is February (2.32").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Potomac, IL
- Average snowfall days in December: 8 days
The month with the highest number of snowfall days is January (9.8 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
Potomac, IL
- Average daylight in December: 9h and 24min
The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in December: 4h and 24min
The month with the most sunshine is June (Average sunshine: 10h and 0min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in December
Potomac, IL
- Average sunshine days in December: 15.9 days
The month with the most sunshine days is November (18.7 days).
The month with the least sunshine days is July (9.5 days).
Average UV index in December
Potomac, IL
- Average UV index in December: 1
The months with the highest UV index are June, July and August (UV index 6).
The month with the lowest UV index is December (UV index 1).
Average cloud cover in December
Potomac, IL
- Average cloud cover in December: 55
The month with the most cloud cover is January (Cloud cover 59).
The months with the least cloud cover are June, August and September (Cloud cover 33).
Average visibility in December
Potomac, IL
- Average visibility in December: 6mi
The months with the highest visibility are January, February, March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are July and August (5mi).
