Columbia Heights, MN 55421 Frost Dates
55421, near Columbia Heights, MN: the frost window
Typically, the last spring freeze lands around 04/30, roughly 245 days out. Fall's first freeze usually shows up around 10/08, roughly 159 days after the last spring frost.
The USDA Plant Hardiness Zone Map puts Columbia Heights 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
Columbia Heights'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 04/30 isn't a guarantee
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 05/17 and only about 1 year in 10 sees frost after that.
Columbia Heights against the rest of the dataset
Columbia Heights's growing season runs about 159 days, ranking 32,591 of 40,283 US ZIP codes measured here, longest to shortest. Within MN, it ranks 245 of 943.
Learn more
Two guides worth reading on 55421: local microclimates, on what one yard in Columbia Heights can differ from the 55421 normal, and zone vs. frost date, on why Zone 5a and Columbia Heights's frost date answer different questions.