Duluth, MN 55802 Frost Dates
55802, near Duluth, MN: the frost window
Typically, the last spring freeze lands around 05/14, roughly 259 days out. Fall's first freeze usually shows up around 10/12, roughly 149 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Duluth 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
Duluth'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 05/14 isn't a guarantee
05/14 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/24 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 06/01 and only about 1 year in 10 sees frost after that.
Duluth against the rest of the dataset
About 149 days separate Duluth's last and first frost, putting it 35,473 of 40,283 ZIP codes nationally. Within MN, it ranks 558 of 943.
Learn more
Two guides worth reading on 55802: local microclimates, on what one yard in Duluth can differ from the 55802 normal, and zone vs. frost date, on why Zone 5a and Duluth's frost date answer different questions.