Southport, IN 46237 Frost Dates
46237, near Southport, IN: the frost window
Typically, the last spring freeze lands around 04/20, roughly 235 days out. Fall's first freeze usually shows up around 10/21, roughly 183 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Southport in Zone 6a (-10 to -5°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
Southport's growing season runs out in roughly 8 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
04/20 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/06 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/05 and only about 1 year in 10 sees frost after that.
Southport against the rest of the dataset
Southport's growing season runs about 183 days, ranking 23,876 of 40,283 US ZIP codes measured here, longest to shortest. Within IN, it ranks 418 of 927.
Learn more
Two guides worth reading on 46237: zone vs. frost date, on why Zone 6a and Southport's frost date answer different questions, and the frost range, on how to read the range around Southport's dates instead of trusting one.