Ontonagon, MI 49925 Frost Dates
When can you plant in Ontonagon, MI?
Around 05/26 is the usual last spring frost, about 271 days away. The first fall frost typically arrives around 09/27, about 123 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 Ontonagon, not a forecast for this year.
What to do before the first frost
About 4 weeks of growing season left in Ontonagon before the first fall frost — a cold frame or row cover can stretch harvest weeks past that date.
How much risk comes with planting early here
05/26 is the middle of 30 years of NOAA records, not a promise. Plant by 05/09 and you're betting against frost in roughly 9 years out of 10. 06/08 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Ontonagon compares
Ontonagon's growing season runs about 123 days, ranking 38,905 of 40,283 US ZIP codes measured here, longest to shortest. Within MI, it ranks 1,089 of 1,153.
Learn more
zone vs. frost date covers why Zone 4b and Ontonagon's frost date answer different questions. the frost range covers how to read the range around Ontonagon's dates instead of trusting one.