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

Planting zone for 59530 — Inverness, MT

ZIP code 59530 (Inverness, Hill County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 21 and the first fall frost September 19.

Where ZIP 59530 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 21
First frostSep 19
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 Inverness, 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 Inverness, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 21median — 50% chance of a later frost
Safe for tender plantsJune 6only 10% chance of frost after
First fall frostSeptember 19median — 10% chance by Sep 3
Growing season119 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 7 and returns around September 29.

From the NOAA station Joplin, MT — 4 miles away, elevation 3,324 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 59530

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 9 – Apr 23
SpinachSow outdoors · Apr 9 – Apr 30
Broccoli, cabbageStart indoors · Mar 12 – Mar 26
Broccoli, cabbageTransplant · Apr 30 – May 14
Onion setsPlant outdoors · Apr 23 – May 7
PotatoesPlant outdoors · Apr 30 – May 14
LettuceSow outdoors · Apr 23 – May 7
Carrots, beetsSow outdoors · Apr 30 – May 14
TomatoesStart indoors · Mar 26 – Apr 9
TomatoesTransplant · May 28 – Jun 11
Peppers, eggplantStart indoors · Mar 12 – Mar 26
Peppers, eggplantTransplant · Jun 4 – Jun 18
BeansSow outdoors · May 28 – Jun 11
Sweet cornSow outdoors · May 28 – Jun 11
Cucumbers, squashSow outdoors · May 28 – Jun 11
Fall lettuce, spinachSow outdoors · Jul 25 – Aug 8
GarlicPlant cloves · Sep 5 – Oct 10
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 21) and first fall frost (Sep 19) 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 59530 came on Mar 29 — 19 days earlier than the 1991–2020 average (Apr 17).

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 Montana

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

Trees 21

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 77

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °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 °FBarclay's willow15 ft · high shade tolerance · to −43 °F

Wildflowers & perennials 189

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 bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °F

Grasses 141

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 Inverness, MT.

Soil in Inverness, MT

The soil mapped at the center of ZIP 59530 is Scobey — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up
pH7.0neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2%moderate
Hydrologic groupCwater soaks in slowly
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Scobey-Kevin clay loams, 0 to 4 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 59530; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Inverness, MT

Summer high84 °Faverage high, July
Winter low8 °Faverage low, January
Hot days20days a year at 90 °F or more
Freezing nights189nights a year at 32 °F or less
Growing degree days1,771base 50 °F — the season’s usable heat
Longest day16 h 08 mindaylight on June 21
Shortest day8 h 17 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation10.8 inper year, rain and melted snow
Snowfall35 inper year; 58 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 29 °F, low 8 °F 29°8° JanFebruary: average high 33 °F, low 10 °F 33°10° FebMarch: average high 43 °F, low 19 °F 43°19° MarApril: average high 55 °F, low 29 °F 55°29° AprMay: average high 66 °F, low 38 °F 66°38° MayJune: average high 73 °F, low 46 °F 73°46° JunJuly: average high 84 °F, low 52 °F 84°52° JulAugust: average high 82 °F, low 50 °F 82°50° AugSeptember: average high 71 °F, low 41 °F 71°41° SepOctober: average high 56 °F, low 30 °F 56°30° OctNovember: average high 41 °F, low 19 °F 41°19° NovDecember: average high 31 °F, low 10 °F 31°10° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.36 in precipitation, 8 in snowfall 0.4❄8 JanFebruary: 0.28 in precipitation, 5.4 in snowfall 0.3❄5 FebMarch: 0.34 in precipitation, 4.4 in snowfall 0.3❄4 MarApril: 0.82 in precipitation, 3 in snowfall 0.8❄3 AprMay: 1.59 in precipitation, 0.4 in snowfall 1.6 MayJune: 2.47 in precipitation, 0.2 in snowfall 2.5 JunJuly: 1.34 in precipitation 1.3 JulAugust: 1.05 in precipitation 1.1 AugSeptember: 1.06 in precipitation 1.1 SepOctober: 0.65 in precipitation, 2.4 in snowfall 0.7❄2 OctNovember: 0.50 in precipitation, 5.3 in snowfall 0.5❄5 NovDecember: 0.30 in precipitation, 6.2 in snowfall 0.3❄6 Dec

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

Nearby ZIP codes

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

595403b
Rudyard, MT · 6 mi
595284a
Hingham, MT · 12 mi
595314a
Joplin, MT · 13 mi
595224a
Chester, MT · 13 mi
595253b
Gildford, MT · 20 mi
594614a
Lothair, MT · 25 mi
595324a
Kremlin, MT · 28 mi
595454a
Whitlash, MT · 33 mi

Montana planting zones →

Questions about 59530

What planting zone is ZIP code 59530?

ZIP code 59530 (Inverness, MT) 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 Inverness, MT?

The median last spring frost (32 °F) near 59530 is May 21; after June 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Joplin station.

When is the first frost in Inverness, MT?

The median first fall frost near 59530 is September 19, giving a median frost-free growing season of 119 days.

When should I plant tomatoes in 59530?

Start tomato seeds indoors around Mar 26 – Apr 9 and set transplants outside around May 28 – Jun 11, one to three weeks after the median last frost.

How much rain and snow does 59530 get?

About 10.8 inches of precipitation a year and 35 inches of snowfall (NOAA 1991–2020 normals, Joplin station).

How hot do summers get in Inverness, MT?

The average high peaks at 84 °F in July, with about 20 days a year at 90 °F or more.

What kind of soil does 59530 have?

The USDA soil survey maps Scobey at the center of ZIP 59530: clay loam, well drained, pH about 7.0 (neutral).

Did spring come early in Inverness, MT in 2026?

Spring leaf-out near 59530 came on Mar 29 in 2026, 19 days earlier than the 1991–2020 average (Apr 17), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Inverness, MT?

Long-day onions: the longest day near 59530 is 16 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).