Chicago, IL 60668 Frost Dates
60668, near Chicago, IL: the frost window
The last spring frost here typically falls around 04/11, about 226 days from today. Fall's first freeze usually shows up around 10/31, roughly 201 days after the last spring frost.
Zone 6b (-5 to 0°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Chicago, not a forecast for this year.
Stretching the season past the first frost
Chicago's growing season runs out in roughly 9 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
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
Chicago's growing season runs about 201 days, ranking 17,421 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 215 of 1,548.
Learn more
Two guides worth reading on 60668: the frost range, on how to read the range around Chicago's dates instead of trusting one, and local microclimates, on what one yard in Chicago can differ from the 60668 normal.