Mazon, IL 60444 Frost Dates
Frost dates for Mazon, IL, ZIP 60444
Around 04/20 is the usual last spring frost, about 235 days away. The first fall frost typically arrives around 10/23, about 184 frost-free days later.
The USDA Plant Hardiness Zone Map puts Mazon in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 5b around Mazon has about 8 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 04/20 isn't a guarantee
04/20 is the middle of 30 years of NOAA records, not a promise. Plant by 04/06 and you're betting against frost in roughly 9 years out of 10. 05/06 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Mazon compares
Mazon's growing season runs about 184 days, ranking 23,595 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 872 of 1,548.
Learn more
the frost range explains how to read the range around Mazon's dates instead of trusting one, and local microclimates explains what one yard in Mazon can differ from the 60444 normal.