St. Charles, IL 60174 Frost Dates
St. Charles, IL: when does the frost end?
Typically, the last spring freeze lands around 04/19, roughly 234 days out. Fall's first freeze usually shows up around 10/23, roughly 185 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts St. Charles in Zone 5b (-15 to -10°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
With roughly 8 weeks until St. Charles's first fall frost, a row cover or cold frame is what stretches the last few weeks of harvest here.
Why 04/19 isn't a guarantee
04/19 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/05 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/04 and only about 1 year in 10 sees frost after that.
St. Charles against the rest of the dataset
About 185 days separate St. Charles's last and first frost, putting it 23,068 of 40,283 ZIP codes nationally. Within IL, it ranks 820 of 1,548.
Learn more
Before leaning on 60174's figures: local microclimates explains what one yard in St. Charles can differ from the 60174 normal, while zone vs. frost date explains why Zone 5b and St. Charles's frost date answer different questions.