Little Sioux, IA 51545 Frost Dates
51545, near Little Sioux, IA: the frost window
Around 05/01 is the usual last spring frost, about 246 days away. Fall's first freeze usually shows up around 10/03, roughly 155 days after the last spring frost.
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 Little Sioux, not a forecast for this year.
Stretching the season past the first frost
Little Sioux's growing season runs out in roughly 5 weeks — a cold frame or greenhouse kit is the usual way to keep cool-weather crops going past the first frost.
How much risk comes with planting early here
05/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/17 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/12 and only about 1 year in 10 sees frost after that.
Little Sioux against the rest of the dataset
Little Sioux's growing season runs about 155 days, ranking 34,163 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 886 of 1,042.
Learn more
Two guides worth reading on 51545: local microclimates, on what one yard in Little Sioux can differ from the 51545 normal, and zone vs. frost date, on why Zone 5a and Little Sioux's frost date answer different questions.