Alexander, IA 50420 Frost Dates
50420, near Alexander, IA: the frost window
Typically, the last spring freeze lands around 04/30, roughly 245 days out. Fall's first freeze usually shows up around 10/10, roughly 162 days after the last spring frost.
Alexander sits in USDA Zone 5a (-20 to -15°F average annual minimum). The dates above are NOAA's 1991-2020 normal at the nearest reporting station, a 30-year average, not a forecast.
Stretching the season past the first frost
Alexander'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.
The actual range around Alexander's last frost
04/30 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.
Alexander against the rest of the dataset
About 162 days separate Alexander's last and first frost, putting it 31,884 of 40,283 ZIP codes nationally. Within IA, it ranks 738 of 1,042.
Learn more
Two guides worth reading on 50420: zone vs. frost date, on why Zone 5a and Alexander's frost date answer different questions, and the frost range, on how to read the range around Alexander's dates instead of trusting one.