December weather forecastRochester, IL
December
Weather in December
December, the first month of the winter in Rochester, is still a cold month, with an average temperature varying between 28.2°F (-2.1°C) and 38.7°F (3.7°C).Temperature
The onset of December comes with a shift in the average high-temperature, falling from a fresh 50.2°F (10.1°C) in November to an icy 38.7°F (3.7°C). An average low-temperature of 28.2°F (-2.1°C) is observed during December nights.Humidity
The average relative humidity in December is 78%.Rainfall
The month with the least rainfall is December, when the rain falls for 7.5 days and typically collects 1.14" (29mm) of precipitation.Snowfall
January through April, November and December are months with snowfall. In Rochester, in December, snow falls for 6.5 days, with typically accumulated 1.06" (27mm) of snow. Throughout the year, there are 27.9 snowfall days, and 6.14" (156mm) of snow is accumulated.Daylight
The month with the shortest days in Rochester is December, with an average of 9h and 24min of daylight.On the first day of the month, sunrise is at 7:00 am and sunset at 4:34 pm. On the last day of December, sunrise is at 7:19 am and sunset at 4:43 pm CST.
Sunshine
In Rochester, Illinois, the average sunshine in December is 4.7h.UV index
January, February, November and December, with an average maximum UV index of 2, are months with the lowest UV index. A UV Index reading of 2, and below, represents a minimal health vulnerability from exposure to the Sun's UV rays for the ordinary person.Note: A maximum daily UV index of 2 during December morphs into the following directions:
While sun exposure does not greatly affect most, individuals with fair skin, babies, and children always need vigilant safeguarding. Solar radiation peaks around mid-day, so it's wise to limit exposure to the Sun at this time. Consider a wide-brim hat essential for effective sun defense covering your face, neck, and eyes. Beware! The strength of the UV rays is increased nearly double-fold by the reflection of the snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in December
Rochester, IL
- Average high temperature in December: 38.7°F
The warmest month (with the highest average high temperature) is July (82.8°F).
The month with the lowest average high temperature is January (33.4°F).
- Average low temperature in December: 28.2°F
The month with the highest average low temperature is July (66°F).
The coldest month (with the lowest average low temperature) is January (21.4°F).
Average pressure in December
Rochester, IL
- Average pressure in December: 30.12"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Rochester, IL
- Average wind speed in December: 9.8mph
The windiest month (with the highest average wind speed) is January (10.4mph).
The calmest months (with the lowest average wind speed) are July and August (6.2mph).
Average humidity in December
Rochester, IL
- Average humidity in December: 78%
The month with the highest relative humidity is July (84%).
The month with the lowest relative humidity is October (70%).
Average rainfall in December
Rochester, IL
- Average rainfall in December: 1.14"
The wettest month (with the highest rainfall) is April (2.64").
The driest month (with the least rainfall) is December (1.14").
Average rainfall days in December
Rochester, IL
- Average rainfall days in December: 7.5 days
The month with the highest number of rainy days is May (17.7 days).
The month with the least rainy days is February (6.2 days).
Average snowfall in December
Rochester, IL
- Average snowfall in December: 1.06"
The month with the highest snowfall is February (1.85").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in December
Rochester, IL
- Average snowfall days in December: 6.5 days
The month with the highest number of snowfall days is January (8.3 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
Rochester, IL
- Average daylight in December: 9h and 24min
The month with the longest days is June (Average daylight: 14h and 54min).
The month with the shortest days is December (Average daylight: 9h and 24min).
- Average sunshine in December: 4h and 42min
The month with the most sunshine is June (Average sunshine: 10h and 24min).
The month with the least sunshine is January (Average sunshine: 4h and 12min).
Average sunshine days in December
Rochester, IL
- Average sunshine days in December: 18.1 days
The month with the most sunshine days is October (18.7 days).
The month with the least sunshine days is July (11 days).
Average UV index in December
Rochester, 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
Rochester, IL
- Average cloud cover in December: 51
The month with the most cloud cover is January (Cloud cover 55).
The month with the least cloud cover is June (Cloud cover 29).
Average visibility in December
Rochester, 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).
