Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 55708 — Biwabik, MN

ZIP code 55708 (Biwabik, St. Louis County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 12 and the first fall frost October 1.

Where ZIP 55708 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.

Zone3b−35 to −30 °F

Coldest night−37.2 to −34.4 °C

Last frostMay 12

First frostOct 1

2012 zone3b

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 3b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Biwabik, MN…

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 Biwabik, MN

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 12median — 50% chance of a later frost

Safe for tender plantsMay 28only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 18

Growing season141 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 3 and returns around October 13.

From the NOAA station Eveleth Wwtp, MN — 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 55708

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 31 – Apr 14

SpinachSow outdoors · Mar 31 – Apr 21

Broccoli, cabbageStart indoors · Mar 3 – Mar 17

Broccoli, cabbageTransplant · Apr 21 – May 5

Onion setsPlant outdoors · Apr 14 – Apr 28

PotatoesPlant outdoors · Apr 21 – May 5

LettuceSow outdoors · Apr 14 – Apr 28

Carrots, beetsSow outdoors · Apr 21 – May 5

TomatoesStart indoors · Mar 17 – Mar 31

TomatoesTransplant · May 19 – Jun 2

Peppers, eggplantStart indoors · Mar 3 – Mar 17

Peppers, eggplantTransplant · May 26 – Jun 9

BeansSow outdoors · May 19 – Jun 2

Sweet cornSow outdoors · May 19 – Jun 2

Cucumbers, squashSow outdoors · May 19 – Jun 2

Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20

GarlicPlant cloves · Sep 17 – Oct 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 12) and first fall frost (Oct 1) 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 55708 came on May 4 — 4 days later than the 1991–2020 average (Apr 30).

average
Apr 302026
May 4

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 Biwabik, MN

The soil mapped at the center of ZIP 55708 is McQuade — loam, poorly drained. Much of the area is built over (urban land); this is the natural soil underneath.

TextureLoama good balance for most vegetables

pH4.9strongly acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter8%high

Hydrologic groupC/Dslow when drained; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Urbanland-McQuade-Buhl complex, 0 to 12 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 55708; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Biwabik, MN

Summer high78 °Faverage high, July

Winter low−7 °Faverage low, January

Hot days1days a year at 90 °F or more

Freezing nights223nights a year at 32 °F or less

Growing degree days1,347base 50 °F — the season’s usable heat

Longest day15 h 59 mindaylight on June 21

Shortest day8 h 26 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation28.1 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Embarrass, MN (9 mi away); precipitation: Embarrass, MN (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Embarrass, MN · 11 mi

557343b

Eveleth, MN · 13 mi

557683b

Mountain Iron, MN · 15 mi

557633b

Makinen, MN · 15 mi

Minnesota planting zones →

Questions about 55708

What planting zone is ZIP code 55708?

ZIP code 55708 (Biwabik, MN) is in USDA hardiness zone 3b on the 2023 map: the coldest night of an average winter reaches −35 to −30 °F (−37.2 to −34.4 °C).

When is the last frost in Biwabik, MN?

The median last spring frost (32 °F) near 55708 is May 12; after May 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Eveleth Wwtp station.

When is the first frost in Biwabik, MN?

The median first fall frost near 55708 is October 1, giving a median frost-free growing season of 141 days.

When should I plant tomatoes in 55708?

Start tomato seeds indoors around Mar 17 – Mar 31 and set transplants outside around May 19 – Jun 2, one to three weeks after the median last frost.

How much rain and snow does 55708 get?

About 28.1 inches of precipitation a year (NOAA 1991–2020 normals, Embarrass station).

How hot do summers get in Biwabik, MN?

The average high peaks at 78 °F in July, with about 1 days a year at 90 °F or more.

What kind of soil does 55708 have?

The USDA soil survey maps McQuade at the center of ZIP 55708: loam, poorly drained, pH about 4.9 (strongly acidic).

Did spring come early in Biwabik, MN in 2026?

Spring leaf-out near 55708 came on May 4 in 2026, 4 days later than the 1991–2020 average (Apr 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Biwabik, MN?

Long-day onions: the longest day near 55708 is 15 h 59 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).