Chicago climate
Chicago (Illinois, United States) has a hot-summer humid continental climate (Köppen Dfa). The average temperature over the year is 10 °C50 °F, and about 982 mm39 in of precipitation falls in an average year.
Temperature by month
Precipitation by month
Chicago climate table
| Month | High °C°F | Low °C°F | Mean °C°F | Precip. mmin | Frost days |
|---|---|---|---|---|---|
| Jan | 032 | −523 | −327 | 481.9 | 26 |
| Feb | 033 | −523 | −228 | 542.1 | 25 |
| Mar | 541 | −131 | 236 | 622.4 | 18 |
| Apr | 1050 | 439 | 744 | 943.7 | 3 |
| May | 1559 | 947 | 1253 | 1174.6 | 0 |
| Jun | 2170 | 1559 | 1865 | 1024.0 | 0 |
| Jul | 2577 | 2068 | 2373 | 953.8 | 0 |
| Aug | 2577 | 2068 | 2373 | 1054.1 | 0 |
| Sep | 2271 | 1662 | 1966 | 863.4 | 0 |
| Oct | 1559 | 1049 | 1254 | 993.9 | 0 |
| Nov | 947 | 338 | 643 | 612.4 | 5 |
| Dec | 337 | −229 | 033 | 582.3 | 19 |
| Year | 2577 | −523 | 1050 | 98239 | 96 |
“Year” row: highest monthly high, lowest monthly low, annual mean and annual total. Frost days are for the whole grid cell.
| Month | Humid. | Cloud | Solar | Daylight |
|---|---|---|---|---|
| Jan | 86% | 71% | 1.6 | 9:27 |
| Feb | 84% | 70% | 2.5 | 10:32 |
| Mar | 82% | 66% | 3.6 | 11:49 |
| Apr | 81% | 63% | 4.7 | 13:17 |
| May | 83% | 64% | 5.4 | 14:32 |
| Jun | 81% | 56% | 6.1 | 15:12 |
| Jul | 78% | 48% | 6.2 | 14:56 |
| Aug | 77% | 48% | 5.3 | 13:51 |
| Sep | 76% | 46% | 4.4 | 12:25 |
| Oct | 77% | 58% | 2.9 | 10:59 |
| Nov | 80% | 63% | 1.9 | 9:45 |
| Dec | 85% | 73% | 1.4 | 9:09 |
Humid. = average relative humidity at 2 m; cloud = average cloud amount; solar = average daily solar energy reaching the ground in kWh/m² (all-sky); daylight in hours:minutes, calculated for the 15th of each month.
What the climate of Chicago is like
The warmest month is August, with an average high of 25 °C77 °F and a low of 20 °C68 °F. The coldest is January, when highs average 0 °C32 °F and lows −5 °C23 °F. Seasons are strongly marked: the warmest month is on average 25.1 °C45.2 °F warmer than the coldest.
Annual precipitation is moderate at about 982 mm39 in. The wettest three-month stretch is May–July, which brings 32% of the annual total. The wettest month is May (117 mm4.6 in), the driest is January (48 mm1.9 in).
Relative humidity ranges from 76% in September to 86% in January. The clearest skies (lowest average cloud amount, 46%) are typical of September. Average wind speed near the ground ranges from 11 km/h (7 mph) in June to 21 km/h (13 mph) in January. Daylight lasts from about 9.1 hours in December to 15.2 hours in June.
A lasting snow cover is typical in December–February, when the average snow depth in the reanalysis exceeds 10 cm (deepest in January, about 16 cm).
Best time to visit Chicago
Based on these averages, the most comfortable months for sightseeing and outdoor activities are June and July and September: average highs of 21 °C70 °F to 25 °C77 °F with 86 mm3.4 in to 102 mm4.0 in of precipitation per month.
The most challenging month is January, which is cold, with average highs of 0 °C32 °F.
Comfort score: months are ranked by how close they come to an average high of 21–28 °C (70–82 °F), lows above 5 °C (41 °F), little precipitation and moderate humidity. The best-ranked months of each place are recommended, even where none meets all of these. These are general rules of thumb applied to long-term averages.
Chicago weather by month
- January0 °C32 °F / −5 °C23 °F
- February0 °C33 °F / −5 °C23 °F
- March5 °C41 °F / −1 °C31 °F
- April10 °C50 °F / 4 °C39 °F
- May15 °C59 °F / 9 °C47 °F
- June21 °C70 °F / 15 °C59 °F
- July25 °C77 °F / 20 °C68 °F
- August25 °C77 °F / 20 °C68 °F
- September22 °C71 °F / 16 °C62 °F
- October15 °C59 °F / 10 °C49 °F
- November9 °C47 °F / 3 °C38 °F
- December3 °C37 °F / −2 °C29 °F
What to pack for Chicago
- Winter (December–February) — highs 032 to 3 °C37 °F, lows −523 to −2 °C29 °F, about 53 mm2.1 in of precipitation a month. Pack a winter coat, hat, gloves and warm, non-slip boots and shoes with good grip, as frost is common.
- Spring (March–May) — highs 541 to 15 °C59 °F, lows −131 to 9 °C47 °F, about 91 mm3.6 in of precipitation a month. Pack a warm coat, layers and closed shoes and an umbrella or light rain jacket.
- Summer (June–August) — highs 2170 to 25 °C77 °F, lows 1559 to 20 °C68 °F, about 101 mm4.0 in of precipitation a month. Pack light layers — T-shirts plus a light sweater or jacket and an umbrella or light rain jacket.
- Autumn (September–November) — highs 947 to 22 °C71 °F, lows 338 to 16 °C62 °F, about 82 mm3.2 in of precipitation a month. Pack long sleeves, a sweater and a medium jacket.
How Chicago compares
Of the 222 places in the United States covered by World Climates, Chicago is the 199th warmest by annual mean temperature and the 111th wettest by annual precipitation. See all of them on the United States climate page.
Places in other countries with the most similar temperature and rainfall pattern: St. Catharines (Canada, Dfa), Kingston (Canada, Dfb) and Hachinohe (Japan, Dfa).
Nearby places
- Joliet 51 km · 10 °C51 °F · 985 mm39 in
- Elgin 56 km · 10 °C49 °F · 983 mm39 in
- Aurora 56 km · 10 °C49 °F · 983 mm39 in
- South Bend 118 km · 10 °C50 °F · 994 mm39 in
- Rockford 128 km · 9 °C48 °F · 967 mm38 in
- Milwaukee 134 km · 9 °C48 °F · 945 mm37 in
- Madison 198 km · 8 °C47 °F · 970 mm38 in
- Grand Rapids 204 km · 9 °C48 °F · 967 mm38 in
Frequently asked questions
What is the warmest month in Chicago?
August is the warmest month in Chicago, with an average high of 25 °C (77 °F) and an average low of 20 °C (68 °F).
What is the coldest month in Chicago?
January is the coldest month, with an average high of 0 °C (32 °F) and an average low of -5 °C (23 °F).
When does it rain the most in Chicago?
May is the wettest month with about 117 mm (4.6 in) of precipitation; January is the driest with about 48 mm (1.9 in).
What is the best time to visit Chicago?
Judging by long-term averages, the most comfortable months are June and July and September.
About this data
All figures are 25-year averages (January 2001 – December 2025) from the NASA POWER project. Temperature, humidity, wind and precipitation come from the MERRA-2 reanalysis (precipitation is the bias-corrected MERRA-2 product), cloud and solar values from CERES satellite data. They describe a grid cell of roughly 50–70 km, not a single weather station, so they can differ from airport records — most of all on coasts, in mountains and for rainfall. Average highs and lows are the monthly mean temperature plus/minus half of the average daily temperature range. Counts of rainy days are not part of this dataset.