Niagara, WI 54156 Frost Dates
When can you plant in Niagara, WI?
Typically, the last spring freeze lands around 05/17, roughly 262 days out. The first fall frost typically arrives around 10/01, about 135 frost-free days later.
Zone 4b (-25 to -20°F average annual minimum) comes from the USDA Plant Hardiness Zone Map; the frost dates above are the 1991-2020 normal at the nearest reporting NOAA station for Niagara, not a forecast for this year.
What to do before the first frost
About 5 weeks of growing season left in Niagara before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
The actual range around Niagara's last frost
05/17 is the middle of 30 years of NOAA records, not a promise. Plant by 05/02 and you're betting against frost in roughly 9 years out of 10. 05/31 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Niagara compares
Niagara's growing season runs about 135 days, ranking 37,874 of 40,283 US ZIP codes measured here, longest to shortest. Within WI, it ranks 773 of 860.
Learn more
zone vs. frost date covers why Zone 4b and Niagara's frost date answer different questions. the frost range covers how to read the range around Niagara's dates instead of trusting one.