Photo: Bobak Ha'Eri · CC BY 3.0Iron Mountain’s winters are colder and snowier than most of the U.S.
A typical July afternoon reaches 80°, a January night drops to 5°, and about 61 inches of snow falls in a normal winter.
A year in Iron Mountain at a glance
Each month’s typical high and low, and what it brings.
What stands out about Iron Mountain’s climate
Compared with towns across the U.S., with Iron Mountain’s place in Michigan beside it.
What a year in Iron Mountain feels like
Typical highs and lows by season and by month, from NOAA’s 30-year normals.
About 135 frost-free days a year
In half of years the last 32° night comes by May 17 and the first by October 1. Frost and day counts come from NOAA’s station at Iron Mtn-kingsford Wwtp, MI, 3 miles from the town’s center, at about the same height.
The 2023 USDA map puts Iron Mountain’s center in zone 4b: the coldest night of a typical winter, averaged over 1991–2020, reaches about −21°. Plant labels use the zone; frost dates tell you when to plant.
Freezing nights by month
Average nights at or below 32°
90° days by month
Average days at 90° or more
About 61 inches of snow a winter
Snow, measured at Iron Mtn-kingsford Wwtp, MI, falls mostly in January. Precipitation (rain plus melted snow) adds up to 29 inches a year; June is the wettest month and February the driest. Rain or snow falls on about 122 days a year.
Rain + melted snow by month
Inches of water
Snowfall by month
Inches of snow
Heating and cooling a home in Iron Mountain
96% of the work is heating, so the furnace matters far more than the air conditioner. Months averaging under 55° run from October through May.
Degree days add up how far each day’s average falls below (heating) or rises above (cooling) 65° over a year. NOAA normals at Iron Mtn-kingsford Wwtp, MI.
Living with Iron Mountain’s climate
What the numbers mean for a garden, a free afternoon and a bad-weather day.
135 frost-free days in zone 4b. The last frost comes by May 17 in half of years, so many gardeners wait a week or two past that to set out tomatoes. The first fall frost comes by Oct 1.
Months with highs of 62–84° and lows of 40° or more: June, July, August and September. 24 miles of trails are waiting.
Parks & trails →Cold waves are 68% of the yearly building losses FEMA expects in Iron Mountain from natural hazards, the largest share. Normals are averages; the hazards page covers the extremes.
Natural hazards →Iron Mountain and its neighbors
Every town next door is within a degree of Iron Mountain in January and July, closer than the 5 km grid can tell apart. Tap a town to see its climate.
Climates most like Iron Mountain’s, farther away
TownRatings’ own comparison of NOAA 1991–2020 normals, not a NOAA product: places of 5,000+ at least 150 miles away, one per state, closest on January low, July high, precipitation and snow.
| Town | Jan. low | July high | Precip. | Snow |
|---|---|---|---|---|
| Iron Mountain, MI | 5° | 80° | 29" | 61" |
| St. Joseph, MN | 3° | 81° | 30" | 57" |
| Rice Lake, WI | 3° | 80° | 33" | 53" |
| Plattsburgh, NY | 9° | 80° | 34" | 50" |
| Watertown, SD | 2° | 81° | 25" | 41" |
Temperatures and rain come from NOAA’s 5 km grid, so each town gets its own value. Snow and frost-free days come from the nearest weather station, so neighbors often share them.
Warmer than it used to be
The last 30 years in Iron Mountain averaged 1.8° warmer than the 1900s. The biggest change is in December (+3.0°).
A bigger shift than in 77% of U.S. towns.
Change by month
The two periods overlap (1991–2000 is in both), which makes the gap a little smaller than it would be between separate periods.
How Iron Mountain compares
Against 12,954 U.S. towns of 2,500 or more (one per 5 km climate cell), with Iron Mountain’s place among Michigan’s.
Iron Mountain weather by month
Highs, lows and precipitation from NOAA’s grid at Iron Mountain’s center; snow, wet days and snow on the ground from Iron Mtn-kingsford Wwtp, MI. 1991–2020 normals.
| Month | High | Low | Rain + melt | Snow | Wet days | Snow on ground | 30-yr range |
|---|---|---|---|---|---|---|---|
| January | 23° | 5° | 1.1" | 14.7" | 10 | 30 | 2° – 24° |
| February | 28° | 6° | 1.0" | 11.2" | 7 | 28 | 4° – 29° |
| March | 39° | 16° | 1.5" | 8.9" | 8 | 23 | 17° – 42° |
| April | 52° | 28° | 2.6" | 7.1" | 10 | 6 | 32° – 47° |
| May | 67° | 40° | 3.2" | 0.2" | 12 | 0 | 46° – 60° |
| June | 76° | 50° | 3.5" | 0.0" | 12 | 0 | 59° – 68° |
| July | 80° | 55° | 3.5" | 0.0" | 12 | 0 | 61° – 72° |
| August | 78° | 53° | 3.1" | 0.0" | 11 | 0 | 60° – 69° |
| September | 69° | 45° | 3.3" | 0.0" | 11 | 0 | 51° – 63° |
| October | 55° | 34° | 3.1" | 0.4" | 12 | 0 | 39° – 50° |
| November | 40° | 24° | 1.9" | 5.5" | 9 | 7 | 23° – 41° |
| December | 28° | 12° | 1.5" | 13.0" | 10 | 23 | 10° – 31° |
| Year | 53° | 31° | 29.3" | 61.0" | 122 | 118 |
How much a month can swing
A normal is an average. February swings the most: from 1991 to 2020 its average ranged from 4° to 29°. August is the most reliable, staying within 9°.
Where Iron Mountain’s numbers come from
Normals are 30-year averages, not a forecast. How TownRatings reads climate data →
- Temperatures and precipitation: NOAA’s gridded 1991–2020 normals for the 5 km cell at Iron Mountain’s center.
- Snow: Iron Mtn-kingsford Wwtp, MI.
- Frost, freezing nights, 90° and 100° days, heating and cooling: Iron Mtn-kingsford Wwtp, MI, 3 miles from the town’s center, at about the same height; the nearest station that passes our checks for distance, height and agreement with the grid.
- Growing zone: USDA Plant Hardiness Zone Map, 2023. USDA Agricultural Research Service and PRISM Group, Oregon State University, prism.oregonstate.edu/phzm, accessed 8 Oct 2026.
- Then and now: NOAA’s gridded normals for 1901–2000 at the same cell.
- Storms and extremes: FEMA National Risk Index (expected annual losses to buildings).
Common questions about Iron Mountain’s climate
What is the weather like in Iron Mountain?
A typical July afternoon reaches 80°, a January night drops to 5°, and about 61 inches of snow falls in a normal winter. Colder January nights than 98% of U.S. towns; cooler July afternoons than 93% of U.S. towns.
How cold does it get in Iron Mountain in winter?
January nights average 5°. About 182 nights a year reach 32° or below and 32 reach 0° or below. In the coldest January of the last 30 years the month averaged 2°.
How much snow does Iron Mountain get?
About 61 inches in a normal winter at Iron Mtn-kingsford Wwtp, MI, most of it in January, with snow on the ground about 118 days a year.
How hot does it get in Iron Mountain?
July, with a typical high of 80° and a low of 55°. About 6 days a year reach 90° (Iron Mtn-kingsford Wwtp, MI).
When is the first and last frost in Iron Mountain?
In half of years the last spring frost (32°) comes by May 17 and the first fall frost by October 1, about 135 frost-free days, at Iron Mtn-kingsford Wwtp, MI.
What growing zone is Iron Mountain in?
Zone 4b on the 2023 USDA Plant Hardiness Zone Map: the coldest night of a typical winter reaches about −21°.
What is the best time of year to visit Iron Mountain?
By one simple rule (highs of 62–84° and lows of 40° or more), June, July, August and September. The rule is ours, not NOAA’s; the month table has the numbers to judge by.
Is Iron Mountain getting warmer?
Yes: 1991–2020 averaged 1.8° warmer than 1901–2000 on NOAA’s grid. A bigger shift than 77% of U.S. towns.
Neighbors talk weather
Gardens, snow, and the best days of the year in Iron Mountain.
Source: NOAA NCEI U.S. Climate Normals, 1991–2020 and 1901–2000; USDA/PRISM 2023 hardiness zones; FEMA National Risk Index. Today’s forecast: National Weather Service.