Chicago, IL 60670 Frost Dates
Frost dates for Chicago, IL, ZIP 60670
Around 04/11 is the usual last spring frost, about 226 days away. The first fall frost typically arrives around 10/31, about 201 frost-free days later.
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.
What to do before the first frost
Zone 6b 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.
Why 04/11 isn't a guarantee
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
Chicago's growing season runs about 201 days, ranking 17,423 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 217 of 1,548.
Learn more
the frost range explains how to read the range around Chicago's dates instead of trusting one, and local microclimates explains what one yard in Chicago can differ from the 60670 normal.