Marengo, IA 52301 Frost Dates
Frost dates for Marengo, IA, ZIP 52301
Around 04/28 is the usual last spring frost, about 243 days away. The first fall frost typically arrives around 10/09, about 164 frost-free days later.
Marengo sits in USDA Zone 5a (-20 to -15°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 5a around Marengo has about 6 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 04/28 isn't a guarantee
04/28 is the middle of 30 years of NOAA records, not a promise. Plant by 04/14 and you're betting against frost in roughly 9 years out of 10. 05/12 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Marengo compares
About 164 days separate Marengo's last and first frost, putting it 30,982 of 40,283 ZIP codes nationally. Within IA, it ranks 590 of 1,042.
Learn more
the frost range explains how to read the range around Marengo's dates instead of trusting one, and local microclimates explains what one yard in Marengo can differ from the 52301 normal.