Naperville, IL 60540 Frost Dates
Frost dates for Naperville, IL, ZIP 60540
Around 04/27 is the usual last spring frost, about 242 days away. The first fall frost typically arrives around 10/17, about 173 frost-free days later.
The USDA Plant Hardiness Zone Map puts Naperville 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 Naperville has about 7 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 04/27 isn't a guarantee
04/27 is the middle of 30 years of NOAA records, not a promise. Plant by 04/12 and you're betting against frost in roughly 9 years out of 10. 05/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Naperville compares
About 173 days separate Naperville's last and first frost, putting it 27,669 of 40,283 ZIP codes nationally. Within IL, it ranks 1,279 of 1,548.
Learn more
zone vs. frost date explains why Zone 5b and Naperville's frost date answer different questions, and the frost range explains how to read the range around Naperville's dates instead of trusting one.