St. Joseph, IL 61873 Frost Dates
St. Joseph, IL: when does the frost end?
The last spring frost here typically falls around 04/20, about 235 days from today. Fall's first freeze usually shows up around 10/21, roughly 182 days after the last spring frost.
Zone 6a (-10 to -5°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 St. Joseph, not a forecast for this year.
Stretching the season past the first frost
With roughly 8 weeks until St. Joseph's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
How much risk comes with planting early here
04/20 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.
St. Joseph against the rest of the dataset
St. Joseph's growing season runs about 182 days, ranking 24,153 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 897 of 1,548.
Learn more
Before leaning on 61873's figures: local microclimates explains what one yard in St. Joseph can differ from the 61873 normal, while zone vs. frost date explains why Zone 6a and St. Joseph's frost date answer different questions.