December weather forecast
Ottawa, IL

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Weather in December

The first month of the winter, December, is also a wintry month in Ottawa, Illinois, with an average temperature varying between 25°F (-3.9°C) and 35.1°F (1.7°C).

Temperature

A shift in Ottawa's weather is observed as November turns into December, with the average high temperature reducing from a chilly 47.1°F (8.4°C) to an icy 35.1°F (1.7°C). During the nights in December, Ottawa experiences a consistent average temperature of 25°F (-3.9°C).

Humidity

The average relative humidity in December in Ottawa is 82%.

Rainfall

In Ottawa, in December, during 8.5 rainfall days, 1.93" (49mm) of precipitation is typically accumulated. In Ottawa, during the entire year, the rain falls for 166.3 days and collects up to 35.35" (898mm) of precipitation.

Snowfall

January through April, October through December are months with snowfall in Ottawa. In Ottawa, in December, snow falls for 9.1 days, with typically accumulated 2.72" (69mm) of snow. Throughout the year, in Ottawa, 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 in Ottawa.
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 in Ottawa. A UV Index value of 2, and less, symbolizes a minimal health vulnerability from unprotected exposure to Sun's UV rays for average individuals.
Note: In December, a daily UV index of 1 turns into the following recommendations:
In contrast to children, who must always be shielded from the sun, most people can tolerate up to an hour of sun exposure without any burns. The Sun is most powerful around mid-day, so it's a good practice to reduce direct exposure. Arm yourself against UV rays' harm with protective apparel and UV-filtering shades. Observe! Snow reflection can nearly intensify the Sun's UV radiation twofold.
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Frequently asked questions

How cold is it in Ottawa in December?

An average high-temperature, in December, in Ottawa, is 35.1°F (1.7°C) and the average low-temperature is 25°F (-3.9°C). In July, the average heat index (a.k.a. 'real feel', 'feels like'), which represents the influence of relative humidity on air temperature, is appraised at 87.8°F (31°C).

What is the average humidity in December in Ottawa?

In December, the average relative humidity in Ottawa is 82%.

How many days does it rain in December in Ottawa?

In Ottawa, during December, the rain falls for 8.5 days and regularly aggregates up to 1.93" (49mm) of precipitation.

How many days does it snow in December in Ottawa?

In Ottawa, Illinois, during December, snow falls for 9.1 days and regularly aggregates up to 2.72" (69mm) of snow.

What is the month with the shortest days in Ottawa?

With an average of 9h and 12min of daylight, December has the shortest days of the year in Ottawa.

How many hours of daylight does Ottawa have in December?

In December, the average day length in Ottawa, Illinois, is 9h and 15min.

When are sunrise and sunset in December in Ottawa?

On the first day of December in Ottawa, Illinois, 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.

How many hours of sunshine does Ottawa have in December?

In Ottawa, the average sunshine duration in December is 4.2h.

What is the month with the lowest UV index in Ottawa?

January and December, with an average maximum UV index of 1, are months with the lowest UV index in Ottawa.

How high is the UV index in December in Ottawa?

The average daily maximum UV index in December in Ottawa, Illinois, is 1. A UV Index estimate of 2, and below, represents a low health threat from unsafe exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in December
Ottawa, IL

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).

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Average pressure in December
Ottawa, IL

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).

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Average wind speed in December
Ottawa, IL

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).

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Average humidity in December
Ottawa, IL

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%).

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Average rainfall in December
Ottawa, IL

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").

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Average rainfall days in December
Ottawa, IL

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).

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Average snowfall in December
Ottawa, IL

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").

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Average snowfall days in December
Ottawa, IL

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).

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Average daylight in December /
Average sunshine in December
Ottawa, IL

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).

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Average sunshine days in December
Ottawa, IL

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).

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Average UV index in December
Ottawa, IL

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).

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Average cloud cover in December
Ottawa, IL

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).

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Average visibility in December
Ottawa, IL

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).

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Ottawa, Illinois, USA

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