Rock Falls, IA 50467 Frost Dates
Frost dates for Rock Falls, IA, ZIP 50467
Around 05/03 is the usual last spring frost, about 248 days away. The first fall frost typically arrives around 10/01, about 150 frost-free days later.
Zone 5a (-20 to -15°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 Rock Falls, not a forecast for this year.
What to do before the first frost
Zone 5a around Rock Falls has about 5 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 Falls's last frost
05/03 is the middle of 30 years of NOAA records, not a promise. Plant by 04/19 and you're betting against frost in roughly 9 years out of 10. 05/15 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Rock Falls compares
Rock Falls's growing season runs about 150 days, ranking 35,447 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 1,023 of 1,042.
Learn more
zone vs. frost date explains why Zone 5a and Rock Falls's frost date answer different questions, and the frost range explains how to read the range around Rock Falls's dates instead of trusting one.