Rock Island, IL 61201 Frost Dates
Frost dates for Rock Island, IL, ZIP 61201
Typically, the last spring freeze lands around 04/24, roughly 239 days out. The first fall frost typically arrives around 10/18, about 176 frost-free days later.
Rock Island 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
Zone 5b around Rock Island 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.
The actual range around Rock Island's last frost
04/24 is the middle of 30 years of NOAA records, not a promise. Plant by 04/09 and you're betting against frost in roughly 9 years out of 10. 05/09 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Rock Island compares
Rock Island's growing season runs about 176 days, ranking 26,374 of 40,283 US ZIP codes measured here, longest to shortest. Within IL, it ranks 1,154 of 1,548.
Learn more
zone vs. frost date explains why Zone 5b and Rock Island's frost date answer different questions, and the frost range explains how to read the range around Rock Island's dates instead of trusting one.