Thompson, IA 50478 Frost Dates
When can you plant in Thompson, IA?
Typically, the last spring freeze lands around 04/30, roughly 245 days out. The first fall frost typically arrives around 10/06, about 158 frost-free days later.
The USDA Plant Hardiness Zone Map puts Thompson 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
About 6 weeks of growing season left in Thompson before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
04/30 is the middle of 30 years of NOAA records, not a promise. Plant by 04/16 and you're betting against frost in roughly 9 years out of 10. 05/14 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Thompson compares
About 158 days separate Thompson's last and first frost, putting it 33,113 of 40,283 ZIP codes nationally. Within IA, it ranks 821 of 1,042.
Learn more
the frost range covers how to read the range around Thompson's dates instead of trusting one. local microclimates covers what one yard in Thompson can differ from the 50478 normal.