St. Augustine, IL 61474 Frost Dates
Frost dates for St. Augustine, IL, ZIP 61474
Around 04/22 is the usual last spring frost, about 237 days away. The first fall frost typically arrives around 10/19, about 177 frost-free days later.
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 St. Augustine, not a forecast for this year.
What to do before the first frost
Zone 5b around St. Augustine has about 7 weeks left before the first fall frost — that's the usual window to get a cold frame up if you want to keep harvesting past it.
Why 04/22 isn't a guarantee
04/22 is the middle of 30 years of NOAA records, not a promise. Plant by 04/07 and you're betting against frost in roughly 9 years out of 10. 05/08 is the safer bet, historically only a 1-in-10 chance of frost that late.
How St. Augustine compares
St. Augustine's growing season runs about 177 days, ranking 26,301 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 1,142 of 1,548.
Learn more
local microclimates explains what one yard in St. Augustine can differ from the 61474 normal, and zone vs. frost date explains why Zone 5b and St. Augustine's frost date answer different questions.