Ontonagon, MI 49929 Frost Dates
When can you plant in Ontonagon, MI?
Around 05/27 is the usual last spring frost, about 272 days away. The first fall frost typically arrives around 10/01, about 127 frost-free days later.
The USDA Plant Hardiness Zone Map puts Ontonagon in Zone 5a (-20 to -15°F average annual minimum); frost dates are NOAA's 1991-2020 station normal, not this year's forecast.
What to do before the first frost
About 5 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.
The actual range around Ontonagon's last frost
05/27 is the middle of 30 years of NOAA records, not a promise. Plant by 05/07 and you're betting against frost in roughly 9 years out of 10. 06/13 is the safer bet, historically only a 1-in-10 chance of frost that late.
How Ontonagon compares
About 127 days separate Ontonagon's last and first frost, putting it 38,638 of 40,283 ZIP codes nationally. Within MI, it ranks 1,060 of 1,153.
Learn more
the frost range covers how to read the range around Ontonagon's dates instead of trusting one. local microclimates covers what one yard in Ontonagon can differ from the 49929 normal.