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

Planting zone for 49839 — Grand Marais, MI

ZIP code 49839 (Grand Marais, Alger County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 27 and the first fall frost October 10.

Where ZIP 49839 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.

Zone5b−15 to −10 °F
Coldest night−26.1 to −23.3 °C
Last frostMay 27
First frostOct 10
2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Grand Marais, 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 Grand Marais, MI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 27median — 50% chance of a later frost
Safe for tender plantsJune 13only 10% chance of frost after
First fall frostOctober 10median — 10% chance by Sep 25
Growing season138 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 9 and returns around October 25.

From the NOAA station Grand Marais 2 E, MI — 11 miles away, elevation 623 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 49839

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 15 – Apr 29
SpinachSow outdoors · Apr 15 – May 6
Broccoli, cabbageStart indoors · Mar 18 – Apr 1
Broccoli, cabbageTransplant · May 6 – May 20
Onion setsPlant outdoors · Apr 29 – May 13
PotatoesPlant outdoors · May 6 – May 20
LettuceSow outdoors · Apr 29 – May 13
Carrots, beetsSow outdoors · May 6 – May 20
TomatoesStart indoors · Apr 1 – Apr 15
TomatoesTransplant · Jun 3 – Jun 17
Peppers, eggplantStart indoors · Mar 18 – Apr 1
Peppers, eggplantTransplant · Jun 10 – Jun 24
BeansSow outdoors · Jun 3 – Jun 17
Sweet cornSow outdoors · Jun 3 – Jun 17
Cucumbers, squashSow outdoors · Jun 3 – Jun 17
Fall lettuce, spinachSow outdoors · Aug 15 – Aug 29
GarlicPlant cloves · Sep 26 – Oct 31
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 27) and first fall frost (Oct 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 49839 came on May 4 — about the same time as the 1991–2020 average (May 3).

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 5b in Michigan

564 plants native to the lower 48 states, recorded in Michigan, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. Each links to its USDA PLANTS profile.

Trees 58

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 103

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 212

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 170

alpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °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 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °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 Grand Marais, MI.

Soil in Grand Marais, MI

The soil mapped at the center of ZIP 49839 is Tawas — muck, very poorly drained.

TextureMucktop layer
pH5.1strongly acidic; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter82.5%high
Hydrologic groupA/Ddrains fast once dried out; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Tawas-Deford mucks.

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 49839; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Grand Marais, MI

Summer high75 °Faverage high, July
Winter low13 °Faverage low, February
Hot days5days a year at 90 °F or more
Freezing nights191nights a year at 32 °F or less
Growing degree days1,703base 50 °F — the season’s usable heat
Longest day15 h 50 mindaylight on June 21
Shortest day8 h 34 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation31.7 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 24 °F, low 14 °F 24°14° JanFebruary: average high 27 °F, low 13 °F 27°13° FebMarch: average high 37 °F, low 20 °F 37°20° MarApril: average high 48 °F, low 28 °F 48°28° AprMay: average high 61 °F, low 40 °F 61°40° MayJune: average high 70 °F, low 48 °F 70°48° JunJuly: average high 75 °F, low 55 °F 75°55° JulAugust: average high 75 °F, low 56 °F 75°56° AugSeptember: average high 68 °F, low 50 °F 68°50° SepOctober: average high 55 °F, low 39 °F 55°39° OctNovember: average high 41 °F, low 29 °F 41°29° NovDecember: average high 31 °F, low 20 °F 31°20° Dec

Precipitation by month inches

0″1″2″3″4″5″January: 1.96 in precipitation 2.0 JanFebruary: 1.42 in precipitation 1.4 FebMarch: 1.45 in precipitation 1.4 MarApril: 2.28 in precipitation 2.3 AprMay: 2.77 in precipitation 2.8 MayJune: 2.75 in precipitation 2.8 JunJuly: 3.09 in precipitation 3.1 JulAugust: 2.74 in precipitation 2.7 AugSeptember: 3.85 in precipitation 3.9 SepOctober: 4.09 in precipitation 4.1 OctNovember: 3.12 in precipitation 3.1 NovDecember: 2.18 in precipitation 2.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Grand Marais 2 E, MI (11 mi away); precipitation: Munsing Lakeshore, MI (27 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

498835a
Seney, MI · 15 mi
498845a
Shingleton, MI · 16 mi
498535a
Mc Millan, MI · 25 mi
498405a
Gulliver, MI · 30 mi
498365a
Germfask, MI · 30 mi
498685a
Newberry, MI · 30 mi
498625b
Munising, MI · 31 mi
498205a
Curtis, MI · 37 mi

Michigan planting zones →

Questions about 49839

What planting zone is ZIP code 49839?

ZIP code 49839 (Grand Marais, MI) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Grand Marais, MI?

The median last spring frost (32 °F) near 49839 is May 27; after June 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Grand Marais 2 E station.

When is the first frost in Grand Marais, MI?

The median first fall frost near 49839 is October 10, giving a median frost-free growing season of 138 days.

When should I plant tomatoes in 49839?

Start tomato seeds indoors around Apr 1 – Apr 15 and set transplants outside around Jun 3 – Jun 17, one to three weeks after the median last frost.

How much rain and snow does 49839 get?

About 31.7 inches of precipitation a year (NOAA 1991–2020 normals, Munsing Lakeshore station).

How hot do summers get in Grand Marais, MI?

The average high peaks at 75 °F in July, with about 5 days a year at 90 °F or more.

What kind of soil does 49839 have?

The USDA soil survey maps Tawas at the center of ZIP 49839: muck, very poorly drained, pH about 5.1 (strongly acidic).

Did spring come early in Grand Marais, MI in 2026?

Spring leaf-out near 49839 came on May 4 in 2026, about the same as the 1991–2020 average (May 3), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Grand Marais, MI?

Long-day onions: the longest day near 49839 is 15 h 50 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).