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

Planting zone for 59078 — Shawmut, MT

ZIP code 59078 (Shawmut, Wheatland County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 26 and the first fall frost September 18.

Where ZIP 59078 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.

Zone4b−25 to −20 °F
Coldest night−31.7 to −28.9 °C
Last frostMay 26
First frostSep 18
2012 zone4a

Was 4a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Shawmut, MT…

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 Shawmut, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 26median — 50% chance of a later frost
Safe for tender plantsJune 13only 10% chance of frost after
First fall frostSeptember 18median — 10% chance by Sep 1
Growing season112 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 11 and returns around September 29.

From the NOAA station Ryegate 18 Nnw, MT — 11 miles away, elevation 4,439 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 59078

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 14 – Apr 28
SpinachSow outdoors · Apr 14 – May 5
Broccoli, cabbageStart indoors · Mar 17 – Mar 31
Broccoli, cabbageTransplant · May 5 – May 19
Onion setsPlant outdoors · Apr 28 – May 12
PotatoesPlant outdoors · May 5 – May 19
LettuceSow outdoors · Apr 28 – May 12
Carrots, beetsSow outdoors · May 5 – May 19
TomatoesStart indoors · Mar 31 – Apr 14
TomatoesTransplant · Jun 2 – Jun 16
Peppers, eggplantStart indoors · Mar 17 – Mar 31
Peppers, eggplantTransplant · Jun 9 – Jun 23
BeansSow outdoors · Jun 2 – Jun 16
Sweet cornSow outdoors · Jun 2 – Jun 16
Cucumbers, squashSow outdoors · Jun 2 – Jun 16
Fall lettuce, spinachSow outdoors · Jul 24 – Aug 7
GarlicPlant cloves · Sep 4 – Oct 9
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 26) and first fall frost (Sep 18) 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 59078 came on Mar 15 — 27 days earlier than the 1991–2020 average (Apr 11).

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 4b in Montana

506 plants native to the lower 48 states, recorded in Montana, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. Each links to its USDA PLANTS profile.

Trees 23

American elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °FDouglas-fir200 ft · blooms mid spring · medium shade tolerance · to −33 °Feastern cottonwood190 ft · blooms spring · high shade tolerance · to −43 °F

Shrubs 87

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °F

Wildflowers & perennials 229

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °F

Grasses 155

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 3

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °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 Shawmut, MT.

Soil in Shawmut, MT

The soil mapped at the center of ZIP 59078 is Cabbart — loam, well drained.

TextureLoama good balance for most vegetables
pH8.2alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Cabbart-Rock outcrop complex, 15 to 60 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 59078; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Shawmut, MT

Summer high82 °Faverage high, July
Winter low12 °Faverage low, January
Hot days15days a year at 90 °F or more
Freezing nights200nights a year at 32 °F or less
Growing degree days1,711base 50 °F — the season’s usable heat
Longest day15 h 49 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)
Precipitation14.3 inper year, rain and melted snow
Snowfall53 inper year; 61 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 36 °F, low 12 °F 36°12° JanFebruary: average high 38 °F, low 12 °F 38°12° FebMarch: average high 47 °F, low 20 °F 47°20° MarApril: average high 55 °F, low 28 °F 55°28° AprMay: average high 64 °F, low 37 °F 64°37° MayJune: average high 72 °F, low 46 °F 72°46° JunJuly: average high 82 °F, low 52 °F 82°52° JulAugust: average high 82 °F, low 50 °F 82°50° AugSeptember: average high 72 °F, low 41 °F 72°41° SepOctober: average high 58 °F, low 29 °F 58°29° OctNovember: average high 45 °F, low 19 °F 45°19° NovDecember: average high 36 °F, low 12 °F 36°12° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.45 in precipitation, 8.3 in snowfall 0.5❄8 JanFebruary: 0.38 in precipitation, 8.3 in snowfall 0.4❄8 FebMarch: 0.69 in precipitation, 10.1 in snowfall 0.7❄10 MarApril: 1.45 in precipitation, 6 in snowfall 1.4❄6 AprMay: 2.27 in precipitation, 0.7 in snowfall 2.3❄1 MayJune: 2.99 in precipitation 3.0 JunJuly: 1.61 in precipitation 1.6 JulAugust: 1.19 in precipitation 1.2 AugSeptember: 1.07 in precipitation, 0.3 in snowfall 1.1 SepOctober: 1.03 in precipitation, 3.6 in snowfall 1.0❄4 OctNovember: 0.62 in precipitation, 7.2 in snowfall 0.6❄7 NovDecember: 0.53 in precipitation, 8.4 in snowfall 0.5❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Ryegate 18 Nnw, MT (11 mi away); precipitation: Ryegate 18 Nnw, MT (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4b.

590744b
Ryegate, MT · 10 mi
594534b
Judith Gap, MT · 18 mi
590364b
Harlowton, MT · 19 mi
590464b
Lavina, MT · 26 mi
590554b
Melville, MT · 27 mi
594644b
Moore, MT · 29 mi
594184b
Buffalo, MT · 32 mi
590674b
Rapelje, MT · 34 mi

Montana planting zones →

Questions about 59078

What planting zone is ZIP code 59078?

ZIP code 59078 (Shawmut, MT) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Shawmut, MT?

The median last spring frost (32 °F) near 59078 is May 26; after June 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ryegate 18 Nnw station.

When is the first frost in Shawmut, MT?

The median first fall frost near 59078 is September 18, giving a median frost-free growing season of 112 days.

When should I plant tomatoes in 59078?

Start tomato seeds indoors around Mar 31 – Apr 14 and set transplants outside around Jun 2 – Jun 16, one to three weeks after the median last frost.

How much rain and snow does 59078 get?

About 14.3 inches of precipitation a year and 53 inches of snowfall (NOAA 1991–2020 normals, Ryegate 18 Nnw station).

How hot do summers get in Shawmut, MT?

The average high peaks at 82 °F in July, with about 15 days a year at 90 °F or more.

What kind of soil does 59078 have?

The USDA soil survey maps Cabbart at the center of ZIP 59078: loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Shawmut, MT in 2026?

Spring leaf-out near 59078 came on Mar 15 in 2026, 27 days earlier than the 1991–2020 average (Apr 11), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Shawmut, MT?

Long-day onions: the longest day near 59078 is 15 h 49 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59078 change?

Yes. The 2012 USDA map put 59078 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.