Herman, MN 56248 Frost Dates
56248, near Herman, MN: the frost window
Typically, the last spring freeze lands around 05/01, roughly 246 days out. Fall's first freeze usually shows up around 10/09, roughly 160 days after the last spring frost.
Herman sits in USDA Zone 4b (-25 to -20°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
Herman'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 05/01 isn't a guarantee
05/01 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 04/18 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.
Herman against the rest of the dataset
Herman's growing season runs about 160 days, ranking 32,503 of 40,283 US ZIP codes measured here, longest to shortest. Within MN, it ranks 229 of 943.
Learn more
Two guides worth reading on 56248: the frost range, on how to read the range around Herman's dates instead of trusting one, and local microclimates, on what one yard in Herman can differ from the 56248 normal.