Illinois weather in May
One place stands in for Illinois here — these are Chicago's numbers, not a statewide average.
Based on 1 weather station, in Chicago. One station — Chicago, where Lake Michigan runs the thermostat; downstate summers come hotter, and the far south of the state sees gentler winters.
Chicago & the Lakefront
Highs near 71°, nights around 51°, and 4.5 in of rain in a typical May.
| Place | Highs / lows | Wet days | The short version |
|---|---|---|---|
| Chicago | 71° / 51° | 8 | Patios open the instant the sun does; carry a shell. |
Each place above has its own page for the full story — what the month feels like, what to pack, and whether the timing is right.