Potomac, IL 61865 Frost Dates
When can you plant in Potomac, IL?
The last spring frost here typically falls around 04/22, about 237 days from today. The first fall frost typically arrives around 10/19, about 180 frost-free days later.
The USDA Plant Hardiness Zone Map puts Potomac in Zone 6a (-10 to -5°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
About 7 weeks of growing season left in Potomac before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/22 isn't a guarantee
04/22 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. 05/08 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Potomac compares
About 180 days separate Potomac's last and first frost, putting it 24,996 of 40,283 ZIP codes nationally. Within IL, it ranks 970 of 1,548.
Learn more
local microclimates covers what one yard in Potomac can differ from the 61865 normal. zone vs. frost date covers why Zone 6a and Potomac's frost date answer different questions.