Walnut, IA 51577 Frost Dates
Frost dates for Walnut, IA, ZIP 51577
Around 04/30 is the usual last spring frost, about 245 days away. The first fall frost typically arrives around 10/02, about 153 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 Walnut, not a forecast for this year.
What to do before the first frost
Zone 5a around Walnut 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.
How much risk comes with planting early here
04/30 is the middle of 30 years of NOAA records, not a promise. Plant by 04/17 and you're betting against frost in roughly 9 years out of 10. 05/15 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Walnut compares
About 153 days separate Walnut's last and first frost, putting it 34,579 of 40,283 ZIP codes nationally. Within IA, it ranks 927 of 1,042.
Learn more
the frost range explains how to read the range around Walnut's dates instead of trusting one, and local microclimates explains what one yard in Walnut can differ from the 51577 normal.