Ottumwa, IA 52501 Frost Dates
Frost dates for Ottumwa, IA, ZIP 52501
The last spring frost here typically falls around 04/23, about 238 days from today. The first fall frost typically arrives around 10/14, about 172 frost-free days later.
Ottumwa 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 Ottumwa 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.
How much risk comes with planting early here
04/23 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. 05/07 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Ottumwa compares
Ottumwa's growing season runs about 172 days, ranking 28,180 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 262 of 1,042.
Learn more
local microclimates explains what one yard in Ottumwa can differ from the 52501 normal, and zone vs. frost date explains why Zone 5b and Ottumwa's frost date answer different questions.