Alpha, IL 61413 Frost Dates
Frost dates for Alpha, IL, ZIP 61413
The last spring frost here typically falls around 04/28, about 243 days from today. The first fall frost typically arrives around 10/12, about 165 frost-free days later.
The USDA Plant Hardiness Zone Map puts Alpha 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 Alpha has about 6 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 04/28 isn't a guarantee
04/28 is the middle of 30 years of NOAA records, not a promise. Plant by 04/15 and you're betting against frost in roughly 9 years out of 10. 05/12 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Alpha compares
About 165 days separate Alpha's last and first frost, putting it 30,678 of 40,283 ZIP codes nationally. Within IL, it ranks 1,494 of 1,548.
Learn more
zone vs. frost date explains why Zone 5b and Alpha's frost date answer different questions, and the frost range explains how to read the range around Alpha's dates instead of trusting one.