Iroquois, IL 60945 Frost Dates
When can you plant in Iroquois, IL?
Typically, the last spring freeze lands around 04/23, roughly 238 days out. The first fall frost typically arrives around 10/14, about 175 frost-free days later.
Iroquois sits in USDA Zone 5b (-15 to -10°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.
What to do before the first frost
About 7 weeks of growing season left in Iroquois before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 04/23 isn't a guarantee
04/23 is the middle of 30 years of NOAA records, not a promise. Plant by 04/10 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 Iroquois compares
At roughly 175 frost-free days, Iroquois places 27,283 of 40,283 ZIP codes in this dataset. Within IL, it ranks 1,219 of 1,548.
Learn more
zone vs. frost date covers why Zone 5b and Iroquois's frost date answer different questions. the frost range covers how to read the range around Iroquois's dates instead of trusting one.