Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated

Planting zone for 49935 — Iron River, MI

ZIP code 49935 (Iron River, Iron County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is June 4 and the first fall frost September 10.

Where ZIP 49935 is

Outlined: the ZIP code area · tap the map for the zone at any spot · scroll or pinch to zoom

Not the official USDA Plant Hardiness Zone Map. Zones come from the 2023 USDA hardiness-zone data by the PRISM Group, Oregon State University; we re-mapped and recolored them. The official map is at planthardiness.ars.usda.gov.

Zone4a−30 to −25 °F
Coldest night−34.4 to −31.7 °C
Last frostJun 4
First frostSep 10
2012 zone4a

Same zone as on the 2012 map. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Iron River, MI…

Forecast data: National Weather Service (api.weather.gov), public domain. This is not a warning service — for official frost and freeze warnings see weather.gov.

Frost dates in Iron River, MI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 4median — 50% chance of a later frost
Safe for tender plantsJune 26only 10% chance of frost after
First fall frostSeptember 10median — 10% chance by Aug 21
Growing season95 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 23 and returns around September 24.

From the NOAA station Stambaugh 2sse, MI — 10 miles away, elevation 1,450 ft. NOAA NCEI U.S. Climate Normals 1991–2020, 32 °F threshold. Low spots and valleys can freeze later in spring than the station.

When to plant vegetables in 49935

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 23 – May 7
SpinachSow outdoors · Apr 23 – May 14
Broccoli, cabbageStart indoors · Mar 26 – Apr 9
Broccoli, cabbageTransplant · May 14 – May 28
Onion setsPlant outdoors · May 7 – May 21
PotatoesPlant outdoors · May 14 – May 28
LettuceSow outdoors · May 7 – May 21
Carrots, beetsSow outdoors · May 14 – May 28
TomatoesStart indoors · Apr 9 – Apr 23
TomatoesTransplant · Jun 11 – Jun 25
Peppers, eggplantStart indoors · Mar 26 – Apr 9
Peppers, eggplantTransplant · Jun 18 – Jul 2
BeansSow outdoors · Jun 11 – Jun 25
Sweet cornSow outdoors · Jun 11 – Jun 25
Cucumbers, squashSow outdoors · Jun 11 – Jun 25
Fall lettuce, spinachSow outdoors · Jul 16 – Jul 30
GarlicPlant cloves · Aug 27 – Oct 1
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 4) and first fall frost (Sep 10) with the rules of thumb U.S. extension services publish. Cool-season crops take a light frost; warm-season crops do best once the soil is above about 60 °F.

When spring arrived in 2026

In 2026, spring leaf-out near 49935 came on Apr 24 — 4 days earlier than the 1991–2020 average (Apr 28).

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 4a in Michigan

443 plants native to the lower 48 states, recorded in Michigan, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. Each links to its USDA PLANTS profile.

Trees 48

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 78

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 168

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °F

Grasses 136

alpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 4

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °F

Source: USDA, NRCS. 2026. The PLANTS Database (plants.usda.gov), National Plant Data Team — state distribution, native status and the “Temperature, Minimum” characteristic. Check light, moisture and soil needs before buying; local nurseries and your state native plant society can confirm what thrives in Iron River, MI.

Soil in Iron River, MI

The soil mapped at the center of ZIP 49935 is Stambaugh — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables
pH5.6moderately acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter5%high
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Stambaugh silt loam, deep water table, 1 to 2 percent slopes, stony.

Soil Survey Staff, Natural Resources Conservation Service, USDA. Soil Survey Geographic (SSURGO) Database, via Soil Data Access, accessed 2026-10-29. The soil at the center point of ZIP 49935; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Iron River, MI

Summer high77 °Faverage high, July
Winter low0 °Faverage low, January
Hot days2days a year at 90 °F or more
Freezing nights211nights a year at 32 °F or less
Growing degree days1,442base 50 °F — the season’s usable heat
Longest day15 h 47 mindaylight on June 21
Shortest day8 h 37 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation30.5 inper year, rain and melted snow
Snowfall67 inper year; 132 days with snow on the ground

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 21 °F, low 0 °F 21°0° JanFebruary: average high 26 °F, low 0 °F 26°0° FebMarch: average high 37 °F, low 9 °F 37°9° MarApril: average high 50 °F, low 24 °F 50°24° AprMay: average high 64 °F, low 37 °F 64°37° MayJune: average high 73 °F, low 47 °F 73°47° JunJuly: average high 77 °F, low 50 °F 77°50° JulAugust: average high 75 °F, low 48 °F 75°48° AugSeptember: average high 67 °F, low 41 °F 67°41° SepOctober: average high 53 °F, low 31 °F 53°31° OctNovember: average high 38 °F, low 21 °F 38°21° NovDecember: average high 26 °F, low 9 °F 26°9° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 1.09 in precipitation, 14.6 in snowfall 1.1❄15 JanFebruary: 0.96 in precipitation, 12.5 in snowfall 1.0❄13 FebMarch: 1.49 in precipitation, 8.7 in snowfall 1.5❄9 MarApril: 2.55 in precipitation, 7.4 in snowfall 2.5❄7 AprMay: 3.17 in precipitation, 0.3 in snowfall 3.2 MayJune: 4.00 in precipitation 4.0 JunJuly: 4.15 in precipitation 4.2 JulAugust: 3.10 in precipitation 3.1 AugSeptember: 3.48 in precipitation 3.5 SepOctober: 3.32 in precipitation, 2.1 in snowfall 3.3❄2 OctNovember: 1.76 in precipitation, 8.2 in snowfall 1.8❄8 NovDecember: 1.46 in precipitation, 13.6 in snowfall 1.5❄14 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Stambaugh 2sse, MI (10 mi away); precipitation: Stambaugh 2sse, MI (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

5 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

499644a
Stambaugh, MI · 9 mi
499154a
Caspian, MI · 10 mi
499274a
Gaastra, MI · 14 mi
545544b
Phelps, WI · 17 mi
545424b
Long Lake, WI · 17 mi
499614b
Sidnaw, MI · 19 mi
499694b
Watersmeet, MI · 23 mi
541204b
Fence, WI · 27 mi

Michigan planting zones →

Questions about 49935

What planting zone is ZIP code 49935?

ZIP code 49935 (Iron River, MI) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Iron River, MI?

The median last spring frost (32 °F) near 49935 is June 4; after June 26 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Stambaugh 2sse station.

When is the first frost in Iron River, MI?

The median first fall frost near 49935 is September 10, giving a median frost-free growing season of 95 days.

When should I plant tomatoes in 49935?

Start tomato seeds indoors around Apr 9 – Apr 23 and set transplants outside around Jun 11 – Jun 25, one to three weeks after the median last frost.

How much rain and snow does 49935 get?

About 30.5 inches of precipitation a year and 67 inches of snowfall (NOAA 1991–2020 normals, Stambaugh 2sse station).

How hot do summers get in Iron River, MI?

The average high peaks at 77 °F in July, with about 2 days a year at 90 °F or more.

What kind of soil does 49935 have?

The USDA soil survey maps Stambaugh at the center of ZIP 49935: silt loam, moderately well drained, pH about 5.6 (moderately acidic).

Did spring come early in Iron River, MI in 2026?

Spring leaf-out near 49935 came on Apr 24 in 2026, 4 days earlier than the 1991–2020 average (Apr 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Iron River, MI?

Long-day onions: the longest day near 49935 is 15 h 47 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).