Chicago, IL 60623 Frost Dates
Frost dates for Chicago, IL, ZIP 60623
Typically, the last spring freeze lands around 04/11, roughly 226 days out. The first fall frost typically arrives around 10/31, about 201 frost-free days later.
Chicago sits in USDA Zone 6a (-10 to -5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 6a around Chicago has about 9 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
The actual range around Chicago's last frost
04/11 is the middle of 30 years of NOAA records, not a promise. Plant by 03/30 and you're betting against frost in roughly 9 years out of 10. 04/27 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Chicago compares
At roughly 201 frost-free days, Chicago places 17,418 of 40,283 ZIP codes in this dataset. Within IL, it ranks 212 of 1,548.
Learn more
zone vs. frost date explains why Zone 6a and Chicago's frost date answer different questions, and the frost range explains how to read the range around Chicago's dates instead of trusting one.