St. Lucas, IA 52166 Frost Dates
When can you plant in St. Lucas, IA?
Typically, the last spring freeze lands around 05/04, roughly 249 days out. The first fall frost typically arrives around 10/04, 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 St. Lucas, not a forecast for this year.
What to do before the first frost
About 5 weeks of growing season left in St. Lucas before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
Why 05/04 isn't a guarantee
05/04 is the middle of 30 years of NOAA records, not a promise. Plant by 04/20 and you're betting against frost in roughly 9 years out of 10. 05/17 is the safer bet, historically only a 1-in-10 chance of frost that late.
How St. Lucas compares
St. Lucas's growing season runs about 151 days, ranking 35,183 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 986 of 1,042.
Learn more
local microclimates covers what one yard in St. Lucas can differ from the 52166 normal. zone vs. frost date covers why Zone 5a and St. Lucas's frost date answer different questions.