Larchwood, IA 51241 Frost Dates
Frost dates for Larchwood, IA, ZIP 51241
Typically, the last spring freeze lands around 05/02, roughly 247 days out. The first fall frost typically arrives around 10/02, about 151 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 Larchwood, not a forecast for this year.
What to do before the first frost
Zone 5a around Larchwood 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 05/02 isn't a guarantee
05/02 is the middle of 30 years of NOAA records, not a promise. Plant by 04/19 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 Larchwood compares
Larchwood's growing season runs about 151 days, ranking 35,099 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 973 of 1,042.
Learn more
zone vs. frost date explains why Zone 5a and Larchwood's frost date answer different questions, and the frost range explains how to read the range around Larchwood's dates instead of trusting one.