Harpers Ferry, IA 52146 Frost Dates
Frost dates for Harpers Ferry, IA, ZIP 52146
Typically, the last spring freeze lands around 04/24, roughly 239 days out. The first fall frost typically arrives around 10/17, about 175 frost-free days later.
Harpers Ferry sits in USDA Zone 5a (-20 to -15°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 5a around Harpers Ferry 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
04/24 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. 05/08 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Harpers Ferry compares
At roughly 175 frost-free days, Harpers Ferry places 27,230 of 40,283 ZIP codes in this dataset. Within IA, it ranks 177 of 1,042.
Learn more
zone vs. frost date explains why Zone 5a and Harpers Ferry's frost date answer different questions, and the frost range explains how to read the range around Harpers Ferry's dates instead of trusting one.