Spirit Lake, IA 51360 Frost Dates
Frost dates for Spirit Lake, IA, ZIP 51360
Around 04/28 is the usual last spring frost, about 243 days away. The first fall frost typically arrives around 10/11, about 164 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 Spirit Lake, not a forecast for this year.
What to do before the first frost
Zone 5a around Spirit Lake 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 04/28 isn't a guarantee
04/28 is the middle of 30 years of NOAA records, not a promise. Plant by 04/14 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 Spirit Lake compares
About 164 days separate Spirit Lake's last and first frost, putting it 30,909 of 40,283 ZIP codes nationally. Within IA, it ranks 577 of 1,042.
Learn more
the frost range explains how to read the range around Spirit Lake's dates instead of trusting one, and local microclimates explains what one yard in Spirit Lake can differ from the 51360 normal.