What is the hottest month in Chicago?

July is Chicago's hottest month, with the highest average daily high of the year. The month-by-month table above shows Chicago's exact average high and low for each month, based on the 1991–2020 climate normals — the standard 30-year reference period meteorologists use.

What is the coldest month in Chicago?

January is Chicago's coldest month, with the lowest average daily low of the year. The averages-by-month chart above gives the exact average high and low for every month, so you can see how cold a typical winter day runs.

How much does it rain in Chicago?

Chicago's total annual precipitation and its wettest and driest months are shown in the rainfall-by-month section above. Those figures are 1991–2020 normals — the average monthly precipitation total across that 30-year window — so they reflect a typical year rather than any single wet or dry season.

What months are best to visit Chicago?

The most comfortable months in Chicago are usually the shoulder seasons — spring and fall — when temperatures sit between the summer peak and winter low and rainfall is moderate. Compare the average high, low, and precipitation for each month in the table above to pick the window that fits the weather you want.

Has Chicago gotten hotter?

Yes. The warming-stripes chart above plots Chicago's annual mean temperature for every complete year of station data from 1959 to 2025, and the trend line fitted to 1959–2025 rises about 3.8°F (+0.57°F per decade) — recent decades average warmer than the start of that window.

What is the record high temperature in Chicago?

Chicago's all-time record high — the hottest single day in the station record — is shown in the records section above, along with the date it occurred. Records are drawn from the nearest long-term weather station's full daily history, which begins in 1958, so they capture the most extreme heat on record, not just a typical summer day.

What is the record low temperature in Chicago?

Chicago's all-time record low and the date it was set appear in the records section above. Like the record high, it comes from the station's full daily history back to 1958, so it reflects the coldest day on record rather than an average winter low.

Chicago, Illinois Climate

Chicago weather by month — average highs and lows, rainfall, all-time records, and the warming record since 1959

Hottest month: 85°FJuly average high
Coldest month: 19°FJanuary average low
Precipitation: 37.9 ina year
Snowfall: 38.4 ina year

1991–2020 NOAA climate normals

At 9:58 AM CDT on Sep 21 it was 60°F in Chicago — 2° below the 62°F typical for that hour (estimated from the Sep 21 normal high of 73°F and low of 55°F, interpolated from the monthly normals).

Chicago weather by month

Average high, low, and rainfall for every month, from Chicago’s 1991–2020 climate normals, the standard 30-year reference period. Each band runs from the month’s average low to its average high: a tall band is a big day-to-night swing.

32°19°

2.0″Jan

36°22°

2.0″Feb

47°31°

2.5″Mar

59°40°

3.8″Apr

71°51°

4.5″May

80°61°

4.1″Jun

85°66°

3.7″Jul

83°65°

4.3″Aug

76°57°

3.2″Sep

63°45°

3.4″Oct

48°34°

2.4″Nov

37°24°

2.1″Dec

Average high → low (°F)Rainfall (inches)1991–2020 normals

Chicago monthly weather averages — average high, average low, and rainfall for each month, from the 1991–2020 U.S. Climate Normals (NOAA).
Month	Avg High	Avg Low	Rainfall
January	32°F	19°F	2.0 in
February	36°F	22°F	2.0 in
March	47°F	31°F	2.5 in
April	59°F	40°F	3.8 in
May	71°F	51°F	4.5 in
June	80°F	61°F	4.1 in
July	85°F	66°F	3.7 in
August	83°F	65°F	4.3 in
September	76°F	57°F	3.2 in
October	63°F	45°F	3.4 in
November	48°F	34°F	2.4 in
December	37°F	24°F	2.1 in
Annual	60°F	43°F	37.9 in

Chicago’s warming record since 1959

Chicago has warmed 3.8°F since 1959 (+0.57°F per decade, 1959–2025 trend)

Not what a typical year looks like, but how the typical year has changed. Each stripe is one complete year’s average temperature at the station, 1959 to 2025, colored against the mean of those years: blue for cooler years, red for warmer ones. The figure under the stripes is the least-squares trend line fitted to 1959–2025 — Chicago averages about 3.8°F warmer by that trend than in 1959.

Compared with the national rankingThe fastest-warming cities ranking fits every city to the same years, 1970–2025, so rates compare like for like. Over that window Chicago warms at +0.62°F per decade, #27 of 66. The figure above uses the station’s own record, 1959–2025, so the two rates differ.

Chicago rainfall by month

Chicago averages 37.9 inches of precipitation a year. The wettest month is May and the driest is February.

Chicago also averages 38.4 inches of snowfall a year.

Chicago temperature records

All-time record high: 104°Fset June 20, 1988
All-time record low: -27°Fset January 20, 1985

Records are drawn from the nearest long-term weather station’s full daily history, so they capture the most extreme single day Chicago has recorded — not a typical seasonal high or low.

Frequently asked

What is the hottest month in Chicago?: July is Chicago's hottest month, with the highest average daily high of the year. The month-by-month table above shows Chicago's exact average high and low for each month, based on the 1991–2020 climate normals — the standard 30-year reference period meteorologists use.
What is the coldest month in Chicago?: January is Chicago's coldest month, with the lowest average daily low of the year. The averages-by-month chart above gives the exact average high and low for every month, so you can see how cold a typical winter day runs.
How much does it rain in Chicago?: Chicago's total annual precipitation and its wettest and driest months are shown in the rainfall-by-month section above. Those figures are 1991–2020 normals — the average monthly precipitation total across that 30-year window — so they reflect a typical year rather than any single wet or dry season.
What months are best to visit Chicago?: The most comfortable months in Chicago are usually the shoulder seasons — spring and fall — when temperatures sit between the summer peak and winter low and rainfall is moderate. Compare the average high, low, and precipitation for each month in the table above to pick the window that fits the weather you want.
Has Chicago gotten hotter?: Yes. The warming-stripes chart above plots Chicago's annual mean temperature for every complete year of station data from 1959 to 2025, and the trend line fitted to 1959–2025 rises about 3.8°F (+0.57°F per decade) — recent decades average warmer than the start of that window.
What is the record high temperature in Chicago?: Chicago's all-time record high — the hottest single day in the station record — is shown in the records section above, along with the date it occurred. Records are drawn from the nearest long-term weather station's full daily history, which begins in 1958, so they capture the most extreme heat on record, not just a typical summer day.
What is the record low temperature in Chicago?: Chicago's all-time record low and the date it was set appear in the records section above. Like the record high, it comes from the station's full daily history back to 1958, so it reflects the coldest day on record rather than an average winter low.