Thayer, IL 62689 Frost Dates
62689, near Thayer, IL: the frost window
Around 04/07 is the usual last spring frost, about 222 days away. Fall's first freeze usually shows up around 10/29, roughly 205 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Thayer in Zone 6a (-10 to -5°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
Thayer's growing season runs out in roughly 9 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/07 isn't a guarantee
04/07 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 03/22 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 04/21 and only about 1 year in 10 sees frost after that.
Thayer against the rest of the dataset
About 205 days separate Thayer's last and first frost, putting it 16,382 of 40,283 ZIP codes nationally. Within IL, it ranks 117 of 1,548.
Learn more
Two guides worth reading on 62689: zone vs. frost date, on why Zone 6a and Thayer's frost date answer different questions, and the frost range, on how to read the range around Thayer's dates instead of trusting one.