Superior, IA 51363 Frost Dates
51363, near Superior, IA: the frost window
The last spring frost here typically falls around 04/28, about 243 days from today. Fall's first freeze usually shows up around 10/11, roughly 164 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 Superior, not a forecast for this year.
Stretching the season past the first frost
Superior'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.
How much risk comes with planting early here
04/28 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/14 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/09 and only about 1 year in 10 sees frost after that.
Superior against the rest of the dataset
Superior's growing season runs about 164 days, ranking 31,237 of 40,283 US ZIP codes measured here, longest to shortest. Within IA, it ranks 649 of 1,042.
Learn more
Two guides worth reading on 51363: the frost range, on how to read the range around Superior's dates instead of trusting one, and local microclimates, on what one yard in Superior can differ from the 51363 normal.