Smithfield, IL 61477 Frost Dates
61477, near Smithfield, IL: the frost window
Typically, the last spring freeze lands around 04/17, roughly 232 days out. Fall's first freeze usually shows up around 10/22, roughly 185 days after the last spring frost.
Smithfield sits in USDA Zone 6a (-10 to -5°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Smithfield's growing season runs out in roughly 8 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
04/17 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/04 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/02 and only about 1 year in 10 sees frost after that.
Smithfield against the rest of the dataset
About 185 days separate Smithfield's last and first frost, putting it 23,347 of 40,283 ZIP codes nationally. Within IL, it ranks 853 of 1,548.
Learn more
Two guides worth reading on 61477: zone vs. frost date, on why Zone 6a and Smithfield's frost date answer different questions, and the frost range, on how to read the range around Smithfield's dates instead of trusting one.