Hennepin, IL 61327 Frost Dates
61327, near Hennepin, IL: the frost window
The last spring frost here typically falls around 04/24, about 239 days from today. Fall's first freeze usually shows up around 10/17, roughly 174 days after the last spring frost.
Zone 5b (-15 to -10°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 Hennepin, not a forecast for this year.
Stretching the season past the first frost
Hennepin's growing season runs out in roughly 7 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
The actual range around Hennepin's last frost
04/24 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/11 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/10 and only about 1 year in 10 sees frost after that.
Hennepin against the rest of the dataset
Hennepin's growing season runs about 174 days, ranking 27,571 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 1,260 of 1,548.
Learn more
Two guides worth reading on 61327: local microclimates, on what one yard in Hennepin can differ from the 61327 normal, and zone vs. frost date, on why Zone 5b and Hennepin's frost date answer different questions.