Mount Ayr, IA 50854 Frost Dates
Frost dates for Mount Ayr, IA, ZIP 50854
Typically, the last spring freeze lands around 04/25, roughly 240 days out. The first fall frost typically arrives around 10/12, about 169 frost-free days later.
Zone 5b (-15 to -10°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 Mount Ayr, not a forecast for this year.
What to do before the first frost
Zone 5b around Mount Ayr 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.
How much risk comes with planting early here
04/25 is the middle of 30 years of NOAA records, not a promise. Plant by 04/10 and you're betting against frost in roughly 9 years out of 10. 05/09 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Mount Ayr compares
Mount Ayr's growing season runs about 169 days, ranking 29,486 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 333 of 1,042.
Learn more
local microclimates explains what one yard in Mount Ayr can differ from the 50854 normal, and zone vs. frost date explains why Zone 5b and Mount Ayr's frost date answer different questions.