Washington, IL 61571 Frost Dates
61571, near Washington, IL: the frost window
Typically, the last spring freeze lands around 04/21, roughly 236 days out. Fall's first freeze usually shows up around 10/17, roughly 178 days after the last spring frost.
Washington 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
Washington'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 04/21 isn't a guarantee
04/21 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.
Washington against the rest of the dataset
At roughly 178 frost-free days, Washington places 25,623 of 40,283 ZIP codes in this dataset. Within IL, it ranks 1,076 of 1,548.
Learn more
Two guides worth reading on 61571: zone vs. frost date, on why Zone 6a and Washington's frost date answer different questions, and the frost range, on how to read the range around Washington's dates instead of trusting one.