Williamsfield, IL 61489 Frost Dates
61489, near Williamsfield, IL: the frost window
Typically, the last spring freeze lands around 04/22, roughly 237 days out. Fall's first freeze usually shows up around 10/14, roughly 174 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Williamsfield in Zone 5b (-15 to -10°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Williamsfield'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.
Why 04/22 isn't a guarantee
04/22 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/08 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/06 and only about 1 year in 10 sees frost after that.
Williamsfield against the rest of the dataset
At roughly 174 frost-free days, Williamsfield places 27,586 of 40,283 ZIP codes in this dataset. Within IL, it ranks 1,264 of 1,548.
Learn more
Two guides worth reading on 61489: local microclimates, on what one yard in Williamsfield can differ from the 61489 normal, and zone vs. frost date, on why Zone 5b and Williamsfield's frost date answer different questions.