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

Planting zone for 54512 — Boulder Junction, WI

ZIP code 54512 (Boulder Junction, Vilas County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 25 and the first fall frost September 21.

Where ZIP 54512 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 25
First frostSep 21
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 Boulder Junction, 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 Boulder Junction, WI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 25median — 50% chance of a later frost
Safe for tender plantsJune 9only 10% chance of frost after
First fall frostSeptember 21median — 10% chance by Sep 3
Growing season117 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 11 and returns around October 1.

From the NOAA station Rest Lake, WI — 11 miles away, elevation 1,611 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 54512

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 13 – Apr 27
SpinachSow outdoors · Apr 13 – May 4
Broccoli, cabbageStart indoors · Mar 16 – Mar 30
Broccoli, cabbageTransplant · May 4 – May 18
Onion setsPlant outdoors · Apr 27 – May 11
PotatoesPlant outdoors · May 4 – May 18
LettuceSow outdoors · Apr 27 – May 11
Carrots, beetsSow outdoors · May 4 – May 18
TomatoesStart indoors · Mar 30 – Apr 13
TomatoesTransplant · Jun 1 – Jun 15
Peppers, eggplantStart indoors · Mar 16 – Mar 30
Peppers, eggplantTransplant · Jun 8 – Jun 22
BeansSow outdoors · Jun 1 – Jun 15
Sweet cornSow outdoors · Jun 1 – Jun 15
Cucumbers, squashSow outdoors · Jun 1 – Jun 15
Fall lettuce, spinachSow outdoors · Jul 27 – Aug 10
GarlicPlant cloves · Sep 7 – Oct 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 25) and first fall frost (Sep 21) 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 54512 came on Apr 23 — 4 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).

Soil in Boulder Junction, WI

The soil mapped at the center of ZIP 54512 is Loxley — peat, very poorly drained.

TexturePeattop layer
pH3.6strongly acidic; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter75%high
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Loxley, Greenwood, and Dawson peats, 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 54512; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Boulder Junction, WI

Summer high78 °Faverage high, July
Winter low0 °Faverage low, January
Hot days3days a year at 90 °F or more
Freezing nights195nights a year at 32 °F or less
Growing degree days1,769base 50 °F — the season’s usable heat
Longest day15 h 46 mindaylight on June 21
Shortest day8 h 38 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation32.3 inper year, rain and melted snow
Snowfall75 inper year; 120 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 20 °F, low 0 °F 20°0° JanFebruary: average high 25 °F, low 3 °F 25°3° FebMarch: average high 37 °F, low 14 °F 37°14° MarApril: average high 50 °F, low 27 °F 50°27° AprMay: average high 65 °F, low 41 °F 65°41° MayJune: average high 74 °F, low 51 °F 74°51° JunJuly: average high 78 °F, low 54 °F 78°54° JulAugust: average high 76 °F, low 53 °F 76°53° AugSeptember: average high 67 °F, low 45 °F 67°45° SepOctober: average high 53 °F, low 33 °F 53°33° OctNovember: average high 37 °F, low 22 °F 37°22° NovDecember: average high 25 °F, low 9 °F 25°9° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 1.21 in precipitation, 16.7 in snowfall 1.2❄17 JanFebruary: 0.93 in precipitation, 12.7 in snowfall 0.9❄13 FebMarch: 1.50 in precipitation, 10.9 in snowfall 1.5❄11 MarApril: 2.54 in precipitation, 7.2 in snowfall 2.5❄7 AprMay: 3.69 in precipitation, 0.3 in snowfall 3.7 MayJune: 4.38 in precipitation 4.4 JunJuly: 4.13 in precipitation 4.1 JulAugust: 3.30 in precipitation 3.3 AugSeptember: 3.66 in precipitation, 0.1 in snowfall 3.7 SepOctober: 3.57 in precipitation, 2.9 in snowfall 3.6❄3 OctNovember: 1.93 in precipitation, 9.1 in snowfall 1.9❄9 NovDecember: 1.42 in precipitation, 15.3 in snowfall 1.4❄15 Dec

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

Nearby ZIP codes

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

545604b
Sayner, WI · 6 mi
545684b
Woodruff, WI · 9 mi
545574a
Presque Isle, WI · 9 mi
545454a
Manitowish Waters, WI · 10 mi
545614b
Star Lake, WI · 11 mi
545584a
Saint Germain, WI · 14 mi
545404a
Land O Lakes, WI · 14 mi
545384a
Lac Du Flambeau, WI · 15 mi

Wisconsin planting zones →

Questions about 54512

What planting zone is ZIP code 54512?

ZIP code 54512 (Boulder Junction, 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 Boulder Junction, WI?

The median last spring frost (32 °F) near 54512 is May 25; after June 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Rest Lake station.

When is the first frost in Boulder Junction, WI?

The median first fall frost near 54512 is September 21, giving a median frost-free growing season of 117 days.

When should I plant tomatoes in 54512?

Start tomato seeds indoors around Mar 30 – Apr 13 and set transplants outside around Jun 1 – Jun 15, one to three weeks after the median last frost.

How much rain and snow does 54512 get?

About 32.3 inches of precipitation a year and 75 inches of snowfall (NOAA 1991–2020 normals, Rest Lake station).

How hot do summers get in Boulder Junction, WI?

The average high peaks at 78 °F in July, with about 3 days a year at 90 °F or more.

What kind of soil does 54512 have?

The USDA soil survey maps Loxley at the center of ZIP 54512: peat, very poorly drained, pH about 3.6 (strongly acidic).

Did spring come early in Boulder Junction, WI in 2026?

Spring leaf-out near 54512 came on Apr 23 in 2026, 4 days earlier than the 1991–2020 average (Apr 27), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Boulder Junction, WI?

Long-day onions: the longest day near 54512 is 15 h 46 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).