Duncombe, IA 50532 Frost Dates
Frost dates for Duncombe, IA, ZIP 50532
The last spring frost here typically falls around 05/03, about 248 days from today. The first fall frost typically arrives around 10/02, 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 Duncombe, not a forecast for this year.
What to do before the first frost
Zone 5a around Duncombe 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.
Why 05/03 isn't a guarantee
05/03 is the middle of 30 years of NOAA records, not a promise. Plant by 04/20 and you're betting against frost in roughly 9 years out of 10. 05/16 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Duncombe compares
Duncombe's growing season runs about 150 days, ranking 35,390 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 1,011 of 1,042.
Learn more
zone vs. frost date explains why Zone 5a and Duncombe's frost date answer different questions, and the frost range explains how to read the range around Duncombe's dates instead of trusting one.