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

Planting zone for 54536 — Iron Belt, WI

ZIP code 54536 (Iron Belt, Iron County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 24 and the first fall frost September 28.

Where ZIP 54536 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 frostMay 24
First frostSep 28
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 Belt, WI…

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 Belt, WI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 24median — 50% chance of a later frost
Safe for tender plantsJune 7only 10% chance of frost after
First fall frostSeptember 28median — 10% chance by Sep 13
Growing season128 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around October 8.

From the NOAA station Hurley, WI — 11 miles away, elevation 1,444 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 54536

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 12 – Apr 26
SpinachSow outdoors · Apr 12 – May 3
Broccoli, cabbageStart indoors · Mar 15 – Mar 29
Broccoli, cabbageTransplant · May 3 – May 17
Onion setsPlant outdoors · Apr 26 – May 10
PotatoesPlant outdoors · May 3 – May 17
LettuceSow outdoors · Apr 26 – May 10
Carrots, beetsSow outdoors · May 3 – May 17
TomatoesStart indoors · Mar 29 – Apr 12
TomatoesTransplant · May 31 – Jun 14
Peppers, eggplantStart indoors · Mar 15 – Mar 29
Peppers, eggplantTransplant · Jun 7 – Jun 21
BeansSow outdoors · May 31 – Jun 14
Sweet cornSow outdoors · May 31 – Jun 14
Cucumbers, squashSow outdoors · May 31 – Jun 14
Fall lettuce, spinachSow outdoors · Aug 3 – Aug 17
GarlicPlant cloves · Sep 14 – Oct 19
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 24) and first fall frost (Sep 28) 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 54536 came on Apr 24 — 3 days earlier than the 1991–2020 average (Apr 27).

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 Wisconsin

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

Trees 45

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 71

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 157

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 133

arctic 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 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °F

Vines 3

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 °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 Belt, WI.

Soil in Iron Belt, WI

The soil mapped at the center of ZIP 54536 is Dawson — peat, very poorly drained.

TexturePeattop layer
DrainageVery poorly drainedconsider raised beds
Organic matter75%high
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Dawson, Greenwood, and Loxley soils, 0 to 1 percent slopes.

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 54536; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Iron Belt, WI

Summer high77 °Faverage high, July
Winter low3 °Faverage low, January
Hot days3days a year at 90 °F or more
Freezing nights185nights a year at 32 °F or less
Growing degree days1,829base 50 °F — the season’s usable heat
Longest day15 h 48 mindaylight on June 21
Shortest day8 h 35 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation37.1 inper year, rain and melted snow
Snowfall140 inper year

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 20 °F, low 3 °F 20°3° JanFebruary: average high 25 °F, low 4 °F 25°4° FebMarch: average high 36 °F, low 15 °F 36°15° MarApril: average high 49 °F, low 28 °F 49°28° AprMay: average high 64 °F, low 41 °F 64°41° MayJune: average high 73 °F, low 51 °F 73°51° JunJuly: average high 77 °F, low 56 °F 77°56° JulAugust: average high 76 °F, low 54 °F 76°54° AugSeptember: average high 67 °F, low 47 °F 67°47° SepOctober: average high 53 °F, low 34 °F 53°34° OctNovember: average high 38 °F, low 23 °F 38°23° NovDecember: average high 26 °F, low 11 °F 26°11° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 2.03 in precipitation, 33.7 in snowfall 2.0❄34 JanFebruary: 1.18 in precipitation, 21.5 in snowfall 1.2❄22 FebMarch: 1.97 in precipitation, 15.8 in snowfall 2.0❄16 MarApril: 3.02 in precipitation, 11.5 in snowfall 3.0❄12 AprMay: 3.59 in precipitation, 1.8 in snowfall 3.6❄2 MayJune: 4.25 in precipitation 4.3 JunJuly: 4.32 in precipitation 4.3 JulAugust: 4.07 in precipitation 4.1 AugSeptember: 4.10 in precipitation 4.1 SepOctober: 4.16 in precipitation, 4 in snowfall 4.2❄4 OctNovember: 2.40 in precipitation, 14 in snowfall 2.4❄14 NovDecember: 1.98 in precipitation, 37.3 in snowfall 2.0❄37 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Hurley, WI (11 mi away); precipitation: Upson, WI (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

545504a
Montreal, WI · 4 mi
545344a
Hurley, WI · 5 mi
545654a
Upson, WI · 7 mi
545254b
Gile, WI · 8 mi
545594b
Saxon, WI · 13 mi
545474a
Mercer, WI · 15 mi
499384b
Ironwood, MI · 16 mi
499114b
Bessemer, MI · 17 mi

Wisconsin planting zones →

Questions about 54536

What planting zone is ZIP code 54536?

ZIP code 54536 (Iron Belt, WI) 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 Belt, WI?

The median last spring frost (32 °F) near 54536 is May 24; after June 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hurley station.

When is the first frost in Iron Belt, WI?

The median first fall frost near 54536 is September 28, giving a median frost-free growing season of 128 days.

When should I plant tomatoes in 54536?

Start tomato seeds indoors around Mar 29 – Apr 12 and set transplants outside around May 31 – Jun 14, one to three weeks after the median last frost.

How much rain and snow does 54536 get?

About 37.1 inches of precipitation a year and 140 inches of snowfall (NOAA 1991–2020 normals, Upson station).

How hot do summers get in Iron Belt, WI?

The average high peaks at 77 °F in July, with about 3 days a year at 90 °F or more.

What kind of soil does 54536 have?

The USDA soil survey maps Dawson at the center of ZIP 54536: peat, very poorly drained.

Did spring come early in Iron Belt, WI in 2026?

Spring leaf-out near 54536 came on Apr 24 in 2026, 3 days earlier than the 1991–2020 average (Apr 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Iron Belt, WI?

Long-day onions: the longest day near 54536 is 15 h 48 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).