Morrison, IA 50657 Frost Dates
Frost dates for Morrison, IA, ZIP 50657
Typically, the last spring freeze lands around 04/29, roughly 244 days out. The first fall frost typically arrives around 10/09, about 160 frost-free days later.
The USDA Plant Hardiness Zone Map puts Morrison 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 Morrison 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 04/29 isn't a guarantee
04/29 is the middle of 30 years of NOAA records, not a promise. Plant by 04/15 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 Morrison compares
Morrison's growing season runs about 160 days, ranking 32,544 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 769 of 1,042.
Learn more
the frost range explains how to read the range around Morrison's dates instead of trusting one, and local microclimates explains what one yard in Morrison can differ from the 50657 normal.