Chicago, IL 60161 Frost Dates
Chicago, IL: when does the frost end?
Typically, the last spring freeze lands around 04/11, roughly 226 days out. Fall's first freeze usually shows up around 10/31, roughly 201 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Chicago in Zone 6a (-10 to -5°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
With roughly 9 weeks until Chicago's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/11 isn't a guarantee
04/11 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/30 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/27 and only about 1 year in 10 sees frost after that.
Chicago against the rest of the dataset
About 201 days separate Chicago's last and first frost, putting it 17,411 of 40,283 ZIP codes nationally. Within IL, it ranks 205 of 1,548.
Learn more
Before leaning on 60161's figures: zone vs. frost date explains why Zone 6a and Chicago's frost date answer different questions, while the frost range explains how to read the range around Chicago's dates instead of trusting one.