The best time to visit US Midwest (Chicago) is Jun–Oct. Month by month, the verdicts rate Jul–Oct as comfortable on both daytime heat and rainfall — 4 months in all.
Cold winters, stormy warm summers
| Month | High °C | High °F | Rainy days | Verdict |
|---|---|---|---|---|
| January | -0.4 | 31 | 29% | Too cold |
| February | 0.6 | 33 | 26% | Too cold |
| March | 4.9 | 41 | 30% | Too cold |
| April | 9.8 | 50 | 42% | Fair |
| May | 14.9 | 59 | 45% | Fair |
| June | 20.7 | 69 | 45% | Fair |
| July | 24.6 | 76 | 42% | Go |
| August | 24.7 | 76 | 42% | Go |
| September | 21.5 | 71 | 35% | Go |
| October | 15.1 | 59 | 34% | Go |
| November | 8.1 | 47 | 30% | Fair |
| December | 2.3 | 36 | 29% | Too cold |
Verdict combines mean daytime high with rainy-day frequency. “Rainy days” is the share of days in the month with at least 1 mm of rain.
February is the driest month, with rain on 26% of days and daytime highs near 0.6°C (33°F). May is the wettest, at 45%. Temperature swings hard across the year — 25.1°C between August (24.7°C / 76°F) and January (-0.4°C / 31°F) — so packing for the wrong month is the main risk. The record rules out too cold in Dec–Mar.