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Will it freeze in Iron Mountain in the next 7 nights?
The earliest overnight low at or below 32°F in the available NWS frost forecast is Tonight: 28°F (Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST).
Tonight: forecast low 28°F. Hard freeze.
NWS forecast period: Thu, Nov 5, 6:00 PM CST to Fri, Nov 6, 6:00 AM CST.
6 of the next 7 nights are forecast at 36°F or colder, cold enough for frost on exposed plants.
- Tonight 28°F Hard freeze · Chance Rain And Snow Showers
- Fri, Nov 6 23°F Hard freeze · Mostly Clear
- Sat, Nov 7 29°F Freeze · Mostly Clear
- Sun, Nov 8 30°F Freeze · Partly Cloudy
- Mon, Nov 9 37°F Above 36°F · Partly Cloudy
- Tue, Nov 10 31°F Freeze · Partly Cloudy
- Wed, Nov 11 31°F Freeze · Slight Chance Rain Showers then Mostly Cloudy
Overnight lows from the National Weather Service forecast for this location. This covers the available forecast window, not the first freeze of the whole season. Frost can form above 32°F on clear, calm nights.
Frost and freeze probabilities
Freeze dates shift from year to year. Spring percentages describe the chance of a freeze after the stated date; fall percentages describe the chance of a freeze by that date. The 10% spring date is the cautious one: a later freeze happens about 1 year in 10.
These dates describe historical probabilities, not this year’s forecast or the earliest and latest possible freezes. Different weather stations or probability thresholds can produce different published dates for the same city.
Average first hard freeze in Iron Mountain
The median first fall hard-freeze date (28°F) is October 5, from NOAA’s 1991–2020 Climate Normals at Iron Mountain Ford Airport. This is the 50% probability date, not a forecast for this year.
| Temperature | Last spring date 90% · 50% · 10% chance of a later freeze | First fall date 10% · 50% · 90% chance of an earlier freeze | Season |
|---|---|---|---|
| 36°F frost possible | May 24 · Jun 5 · Jun 22 | Aug 24 · Sep 12 · Sep 27 | 97 days |
| 32°F freeze | May 10 · May 25 · Jun 6 | Sep 8 · Sep 24 · Oct 7 | 121 days |
| 28°F hard freeze | Apr 28 · May 11 · May 26 | Sep 21 · Oct 5 · Oct 19 | 145 days |
Average high temperature by month
1991–2020 normals at Iron Mountain Ford Airport
Average low temperature by month
Months with lows near or below freezing carry frost risk
Where these frost dates come from
The frost dates for Iron Mountain, MI come from the nearest weather station with freeze statistics in NOAA’s 1991–2020 Climate Normals: Iron Mountain Ford Airport (station USW00094893, elevation 1,149 ft), 2.7 mi from Iron Mountain. Local conditions (valleys, hilltops, distance to water, city heat) can shift frost dates by days or weeks. The hardiness zone is from the 2023 USDA Plant Hardiness Zone Map (USDA ARS and Oregon State University PRISM). See our methodology.
Frost dates near Iron Mountain
| City | Distance | Last spring frost | First fall frost |
|---|---|---|---|
| Kingsford, MI | 2.5 mi | May 25 | Sep 24 |
| Escanaba, MI | 47 mi | May 13 | Oct 7 |
| Ishpeming, MI | 48 mi | May 26 | Sep 25 |
| Gladstone, MI | 50 mi | May 18 | Oct 4 |
| Menominee, MI | 53 mi | May 4 | Oct 11 |
| Marinette, WI | 55 mi | May 4 | Oct 11 |
| Marquette, MI | 59 mi | May 8 | Oct 21 |
| Rhinelander, WI | 68 mi | May 26 | Sep 23 |
| Antigo, WI | 71 mi | May 14 | Sep 30 |
| Sturgeon Bay, WI | 77 mi | May 8 | Oct 13 |
Frequently asked questions
When is the last frost in Iron Mountain?
On average, the last spring frost (32°F) in Iron Mountain is around May 25. In about 1 year in 10 it comes after June 6, and in 9 years in 10 it comes after May 10.
When is the first frost in Iron Mountain?
The first fall frost (32°F) usually arrives around September 24. There’s a 10% chance of a freeze by September 8 and a 90% chance by October 7.
Can it frost in Iron Mountain after the last frost date?
Yes. Frost can form on clear, calm nights even when the air stays above 32°F. Temperatures of 36°F or lower, cold enough for frost on exposed plants, have a 50% chance of occurring after June 5.
What growing zone is Iron Mountain?
Iron Mountain is in USDA Plant Hardiness Zone 4b (average annual extreme minimum temperature −25 to −20°F), based on the 2023 USDA map for ZIP code 49802. See growing zones in Michigan.
More: all Michigan frost dates · Michigan growing zones · frost vs. freeze