Tonica, IL 61370 Frost Dates
Frost dates for Tonica, IL, ZIP 61370
Typically, the last spring freeze lands around 04/24, roughly 239 days out. The first fall frost typically arrives around 10/18, about 176 frost-free days later.
Zone 5b (-15 to -10°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 Tonica, not a forecast for this year.
What to do before the first frost
Zone 5b around Tonica 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 04/24 isn't a guarantee
04/24 is the middle of 30 years of NOAA records, not a promise. Plant by 04/11 and you're betting against frost in roughly 9 years out of 10. 05/08 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Tonica compares
About 176 days separate Tonica's last and first frost, putting it 26,574 of 40,283 ZIP codes nationally. Within IL, it ranks 1,188 of 1,548.
Learn more
the frost range explains how to read the range around Tonica's dates instead of trusting one, and local microclimates explains what one yard in Tonica can differ from the 61370 normal.