Brocton, IL 61917 Frost Dates
Frost dates for Brocton, IL, ZIP 61917
Around 04/21 is the usual last spring frost, about 236 days away. The first fall frost typically arrives around 10/20, about 179 frost-free days later.
Zone 6a (-10 to -5°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 Brocton, not a forecast for this year.
What to do before the first frost
Zone 6a around Brocton 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 04/21 isn't a guarantee
04/21 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. 05/09 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Brocton compares
About 179 days separate Brocton's last and first frost, putting it 25,489 of 40,283 ZIP codes nationally. Within IL, it ranks 1,070 of 1,548.
Learn more
the frost range explains how to read the range around Brocton's dates instead of trusting one, and local microclimates explains what one yard in Brocton can differ from the 61917 normal.