Potomac, IL 61831 Frost Dates
Potomac, IL: when does the frost end?
Around 04/20 is the usual last spring frost, about 235 days away. Fall's first freeze usually shows up around 10/21, roughly 182 days after the last spring frost.
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 Potomac, not a forecast for this year.
Stretching the season past the first frost
With roughly 8 weeks until Potomac's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
The actual range around Potomac's last frost
04/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/07 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/07 and only about 1 year in 10 sees frost after that.
Potomac against the rest of the dataset
About 182 days separate Potomac's last and first frost, putting it 24,264 of 40,283 ZIP codes nationally. Within IL, it ranks 906 of 1,548.
Learn more
Before leaning on 61831's figures: the frost range explains how to read the range around Potomac's dates instead of trusting one, while local microclimates explains what one yard in Potomac can differ from the 61831 normal.