Williamsfield, IL 61428 Frost Dates
Frost dates for Williamsfield, IL, ZIP 61428
The last spring frost here typically falls around 04/21, about 236 days from today. The first fall frost typically arrives around 10/20, about 181 frost-free days later.
Williamsfield sits in USDA Zone 5b (-15 to -10°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
What to do before the first frost
Zone 5b around Williamsfield 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 04/07 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 Williamsfield compares
About 181 days separate Williamsfield's last and first frost, putting it 24,678 of 40,283 ZIP codes nationally. Within IL, it ranks 933 of 1,548.
Learn more
local microclimates explains what one yard in Williamsfield can differ from the 61428 normal, and zone vs. frost date explains why Zone 5b and Williamsfield's frost date answer different questions.