Illinois weather in December 2026

Q: How cold is it in Illinois in December?

Daytime temperatures usually reach 2°C in Chicago, Illinois in December, falling to -7°C at night.

Q: How sunny is it in Illinois in December?

There are normally 3 hours of bright sunshine each day in Chicago, Illinois in December - that's 37% of daylight hours.

Q: Is the sea cold around Illinois in December?

The average sea temperature around Chicago, Illinois in December is 5°C.

Q: Does it rain in Illinois in December?

There are usually 12 days with some rain in Chicago, Illinois in December and the average monthly rainfall is 62mm. Rain may fall as snow in this month.

Expect daytime maximum temperatures of 36°F in Illinois, USA in December based on long-term weather averages. There are 3 hours of sunshine per day on average with 12 days with some rainfall and typically 2.4 inches of rainfall in the month, which might fall as snow.

36
36°F max day temperature
3
3 hours of sunshine per day
12
12 days with some rainfall
19
19°F min night temperature
9
9 hours of daylight per day
0
No heat & humidity
2.4
2.4 inches of monthly rainfall
1
1 (Low) UV index
41
41°F sea temperature

More about Illinois

Illinois by month

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

Recommended for Illinois

First Choice sale: up to £500 off holidays in 2026/2027

Sale

Save up to £500 on holidays (1 May 2026-31 Oct 2027)
10% discount up to £500. Min spend £500. T&Cs apply
Travel between 1st May 2026 & 31st Oct 2027 (inclusive)

Go to First Choice deal >>

Expires at 23:59 on Saturday 28th Feb 2026 · View all First Choice offers

The December weather guide for Illinois (Chicago) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Top Illinois destinations

Below are average maximum temperatures at popular countries, regions and places in Illinois in December. Select a holiday destination to see more weather parameters.

37
Springfield
36
Chicago

All Illinois destinations

Metric (°C) | Imperial (°F)

More about the USA

How cold is it in Illinois in December?

Daytime temperatures usually reach 36°F in Chicago, Illinois in December, falling to 19°F at night.

How sunny is it in Illinois in December?

There are normally 3 hours of bright sunshine each day in Chicago, Illinois in December - that's 37% of daylight hours.

How warm is the sea around Illinois in December?

The average sea temperature around Chicago, Illinois in December is 41°F.

Does it rain in Illinois in December?

There are usually 12 days with some rain in Chicago, Illinois in December and the average monthly rainfall is 2.4 inches. Rain may fall as snow in this month.

Illinois December sunrise & sunset times

Browse the sunrise and sunset times for Illinois in December 2026. Select a month to view Illinois sunrise and sunset times for the next 12 months. The Illinois sunrise and sunset times shown below are for Chicago.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec