Chicago climate by month
What the weather is like
Chicago has a hot-summer humid continental climate (Köppen Dfa): warm summers, cold winters and precipitation in every season.
The warmest month is July, when afternoons average 83° and nights 67°. January is the coolest month, with highs of 32° and lows of 19°. The difference between the warmest and the coolest month is about 50°, a large swing typical of continental interiors.
About 42.2 in of precipitation falls in an average year. May is the wettest month (4.4 in, 13 wet days) and February the driest (2.2 in, 8 wet days). Cloud cover ranges from 29% in July to 51% in December.
The sea reaches about 73° in August. Sea temperatures lag the air by a month or two, so late summer is usually warmer for swimming than early summer.
Compared with Washington, the capital, Chicago is 3.5° cooler on a July afternoon and receives more precipitation over the year.
Year in figures
- Hottest afternoons
- 83° · July
- Coldest nights
- 19° · January
- Wettest month
- May
- Driest month
- February
- Clearest skies
- July · 29% cloud
- Warmest sea
- 73° · August
- Longest day
- 15 h 12 min
- Shortest day
- 9 h 09 min
Twelve months at a glance
Temperature and precipitation
Daily high/low range bars, monthly precipitation columns, sea temperature lineTemperature curve
Average high, low and seaDaylight
Hours between sunrise and sunset on the 15th of each monthClimate normals month by month
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Average high | 32° | 35° | 45° | 56° | 68° | 78° | 83° | 81° | 75° | 62° | 49° | 37° |
| Average low | 19° | 22° | 30° | 40° | 51° | 61° | 67° | 67° | 59° | 46° | 35° | 25° |
| Precipitation | 2.3 in | 2.2 in | 2.8 in | 3.8 in | 4.4 in | 4.4 in | 4.3 in | 4.6 in | 3.5 in | 3.6 in | 3.5 in | 2.6 in |
| Wet days (≥1 mm) | 8.1 | 7.5 | 9.1 | 11.6 | 13.3 | 13.1 | 12.4 | 12.7 | 10.4 | 10.6 | 8.4 | 8.8 |
| Cloud cover | 50% | 47% | 44% | 42% | 39% | 35% | 29% | 30% | 30% | 37% | 46% | 51% |
| Sea temperature | 38° | 36° | 36° | 39° | 45° | 57° | 70° | 73° | 68° | 58° | 49° | 42° |
| Daylight | 9h 28 | 10h 37 | 11h 54 | 13h 20 | 14h 33 | 15h 12 | 14h 56 | 13h 53 | 12h 30 | 11h 07 | 9h 50 | 9h 09 |
| Month score | 31 | 33 | 31 | 43 | 65 | 64 | 57 | 60 | 75 | 65 | 32 | 29 |