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
December's onset corresponds with a shift in the average high-temperature, moving from a frosty 47.1°F (8.4°C) in November to a cold 35.1°F (1.7°C). During December, the average low-temperature is recorded at a subzero cold 25°F (-3.9°C).Humidity
In December, the average relative humidity in Ottawa is 82%.Rainfall
In December, the rain falls for 8.5 days. Throughout December, 1.93" (49mm) of precipitation is accumulated. Throughout the year, there are 166.3 rainfall days, and 35.35" (898mm) of precipitation is accumulated.Snowfall
January through April, October through December are months with snowfall. In Ottawa, in December, during 9.1 snowfall days, 2.72" (69mm) of snow is typically accumulated. Throughout the year, there are 43.4 snowfall days, and 17.76" (451mm) of snow is accumulated.Daylight
With an average of 9h and 12min of daylight, December has the shortest days of the year.On the first day of December, sunrise is at 7:02 am and sunset at 4:26 pm. On the last day of the month, sunrise is at 7:21 am and sunset at 4:36 pm CST.
Sunshine
The average sunshine in December is 4.2h.UV index
January and December, with an average maximum UV index of 1, are months with the lowest UV index. A UV Index reading of 2, and below, represents a low health risk from unprotected exposure to Sun's UV rays for ordinary individuals.Note: The maximum UV index of 1 during December leads to these instructions:
Infants, children, and people with sensitive skin should always have protection against lengthy periods of sun exposure. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. Sun-protective clothing, a long-sleeved shirt and pants, a wide-brimmed hat, and UVA and UVB-blocking sunglasses are particularly helpful in blocking UV radiation's harmful effects. Be mindful! The reflection from snow can increase the Sun's UV radiation nearly twice.
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 much does it snow in December?
What is the month with the shortest days?
How many hours of daylight does Ottawa have in December?
When are sunrise and sunset in December in Ottawa?
How many hours of sunshine does Ottawa have in December?
What is the month with the lowest UV index?
How high is the UV index in December?
Average temperature in December
Ottawa, IL
- Average high temperature in December: 35.1°F
The warmest month (with the highest average high temperature) is July (81°F).
The month with the lowest average high temperature is January (29.1°F).
- Average low temperature in December: 25°F
The month with the highest average low temperature is July (64.2°F).
The coldest month (with the lowest average low temperature) is January (17.2°F).
Average pressure in December
Ottawa, IL
- Average pressure in December: 30.1"Hg
The month with the highest atmospheric pressure is January (30.13"Hg).
The month with the lowest atmospheric pressure is June (29.92"Hg).
Average wind speed in December
Ottawa, IL
- Average wind speed in December: 9.5mph
The windiest month (with the highest average wind speed) is April (10.2mph).
The calmest month (with the lowest average wind speed) is August (6.2mph).
Average humidity in December
Ottawa, IL
- Average humidity in December: 82%
The month with the highest relative humidity is July (85%).
The month with the lowest relative humidity is October (72%).
Average rainfall in December
Ottawa, IL
- Average rainfall in December: 1.93"
The wettest month (with the highest rainfall) is May (5").
The driest month (with the least rainfall) is November (1.81").
Average rainfall days in December
Ottawa, IL
- Average rainfall days in December: 8.5 days
The month with the highest number of rainy days is July (19.9 days).
The month with the least rainy days is February (6.2 days).
Average snowfall in December
Ottawa, IL
- Average snowfall in December: 2.72"
The month with the highest snowfall is February (5.08").
The months with the least snowfall are May, June, July, August and September (0").
Average snowfall days in December
Ottawa, IL
- Average snowfall days in December: 9.1 days
The month with the highest number of snowfall days is January (12.9 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
Ottawa, IL
- Average daylight in December: 9h and 1min
The month with the longest days is June (Average daylight: 15h and 6min).
The month with the shortest days is December (Average daylight: 9h and 12min).
- Average sunshine in December: 4h and 1min
The month with the most sunshine is June (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 54min).
Average sunshine days in December
Ottawa, IL
- Average sunshine days in December: 15.3 days
The month with the most sunshine days is November (17 days).
The month with the least sunshine days is July (7.2 days).
Average UV index in December
Ottawa, IL
- Average UV index in December: 1
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in December
Ottawa, IL
- Average cloud cover in December: 55
The month with the most cloud cover is January (Cloud cover 59).
The month with the least cloud cover is September (Cloud cover 32).
Average visibility in December
Ottawa, IL
- Average visibility in December: 6mi
The months with the highest visibility are March, April, May, June, September, October, November and December (6mi).
The months with the lowest visibility are January, February, July and August (5mi).
Ottawa, Illinois, USA
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