Chicago is warmest in August, averaging 26° by day and 20° at night. The wettest month is July with 109 mm, and the year brings about 895 mm in total.
Month by month
| Month | High | Low | Rain | Daylight | Good for |
|---|---|---|---|---|---|
| January | 1° | -5° | 59 mm | 9.3 h | Cool |
| February | 2° | -6° | 39 mm | 10.3 h | Cool |
| March | 6° | -1° | 84 mm | 11.7 h | Cool |
| April | 10° | 3° | 84 mm | 13.1 h | Cool |
| May | 16° | 9° | 99 mm | 14.4 h | Sightseeing |
| June | 23° | 15° | 90 mm | 15.0 h | Sightseeing |
| July | 25° | 20° | 109 mm | 14.8 h | Mild |
| August | 26° | 20° | 71 mm | 13.7 h | Beach weather |
| September | 23° | 17° | 69 mm | 12.3 h | Sightseeing |
| October | 17° | 10° | 93 mm | 10.8 h | Sightseeing |
| November | 10° | 3° | 42 mm | 9.6 h | Cool |
| December | 4° | -1° | 56 mm | 9.0 h | Cool |
High and low are average daily maximum and minimum, rain is typical monthly total, daylight is the hours between sunrise and sunset mid-month. Climate normals from NASA POWER — averages, not promises.
When to go
Beach weather: August — highs around 26°, nights no colder than 20°, and at most 71 mm of rain in a month.
Walking the city: May, June, September and October — highs of 16–23° and no more than 99 mm of rain a month.