Superior, WI 54880 Frost Dates
When can you plant in Superior, WI?
Typically, the last spring freeze lands around 05/06, roughly 251 days out. The first fall frost typically arrives around 10/09, about 154 frost-free days later.
Superior 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.
What to do before the first frost
About 6 weeks of growing season left in Superior before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Superior's last frost
05/06 is the middle of 30 years of NOAA records, not a promise. Plant by 04/24 and you're betting against frost in roughly 9 years out of 10. 05/25 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Superior compares
About 154 days separate Superior's last and first frost, putting it 34,213 of 40,283 ZIP codes nationally. Within WI, it ranks 460 of 860.
Learn more
zone vs. frost date covers why Zone 4b and Superior's frost date answer different questions. the frost range covers how to read the range around Superior's dates instead of trusting one.