Mellen, WI 54517 Frost Dates
54517, near Mellen, WI: the frost window
Typically, the last spring freeze lands around 05/16, roughly 261 days out. Fall's first freeze usually shows up around 09/30, roughly 136 days after the last spring frost.
Mellen sits in USDA Zone 4a (-30 to -25°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
Mellen's growing season runs out in roughly 5 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
05/16 is the middle of 30 years of NOAA records, not a promise. Getting tender plants in by 05/01 carries real risk, frost has hit that late in about 9 of 10 years here. Wait until 05/27 and only about 1 year in 10 sees frost after that.
Mellen against the rest of the dataset
Mellen's growing season runs about 136 days, ranking 37,744 of 40,283 US ZIP codes measured here, longest to shortest. Within WI, it ranks 762 of 860.
Learn more
Two guides worth reading on 54517: local microclimates, on what one yard in Mellen can differ from the 54517 normal, and zone vs. frost date, on why Zone 4a and Mellen's frost date answer different questions.