Monticello, IA 52252 Frost Dates
Frost dates for Monticello, IA, ZIP 52252
Around 04/27 is the usual last spring frost, about 242 days away. The first fall frost typically arrives around 10/13, about 170 frost-free days later.
The USDA Plant Hardiness Zone Map puts Monticello in Zone 5a (-20 to -15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
Zone 5a around Monticello 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 04/27 isn't a guarantee
04/27 is the middle of 30 years of NOAA records, not a promise. Plant by 04/12 and you're betting against frost in roughly 9 years out of 10. 05/10 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Monticello compares
About 170 days separate Monticello's last and first frost, putting it 29,003 of 40,283 ZIP codes nationally. Within IA, it ranks 299 of 1,042.
Learn more
local microclimates explains what one yard in Monticello can differ from the 52252 normal, and zone vs. frost date explains why Zone 5a and Monticello's frost date answer different questions.