Prophetstown, IL 61277 Frost Dates
61277, near Prophetstown, IL: the frost window
The last spring frost here typically falls around 04/26, about 241 days from today. Fall's first freeze usually shows up around 10/13, roughly 167 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 Prophetstown, not a forecast for this year.
Stretching the season past the first frost
Prophetstown'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.
How much risk comes with planting early here
04/26 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/13 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/11 and only about 1 year in 10 sees frost after that.
Prophetstown against the rest of the dataset
Prophetstown's growing season runs about 167 days, ranking 30,034 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 1,457 of 1,548.
Learn more
Two guides worth reading on 61277: the frost range, on how to read the range around Prophetstown's dates instead of trusting one, and local microclimates, on what one yard in Prophetstown can differ from the 61277 normal.