Archer, IA 51231 Frost Dates
51231, near Archer, IA: the frost window
Around 04/29 is the usual last spring frost, about 244 days away. Fall's first freeze usually shows up around 10/10, roughly 163 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Archer in Zone 5a (-20 to -15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
Stretching the season past the first frost
Archer's growing season runs out in roughly 6 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
Why 04/29 isn't a guarantee
04/29 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/13 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/11 and only about 1 year in 10 sees frost after that.
Archer against the rest of the dataset
Archer's growing season runs about 163 days, ranking 31,548 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 684 of 1,042.
Learn more
Two guides worth reading on 51231: local microclimates, on what one yard in Archer can differ from the 51231 normal, and zone vs. frost date, on why Zone 5a and Archer's frost date answer different questions.