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

Planting zone for 59474 — Shelby, MT

ZIP code 59474 (Shelby, Toole County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 23 and the first fall frost September 16.

Where ZIP 59474 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 23

First frostSep 16

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 Shelby, 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 Shelby, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 23median — 50% chance of a later frost

Safe for tender plantsJune 6only 10% chance of frost after

First fall frostSeptember 16median — 10% chance by Sep 3

Growing season115 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 10 and returns around September 26.

From the NOAA station Shelby, MT — 7 miles away, elevation 3,327 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 59474

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 11 – Apr 25

SpinachSow outdoors · Apr 11 – May 2

Broccoli, cabbageStart indoors · Mar 14 – Mar 28

Broccoli, cabbageTransplant · May 2 – May 16

Onion setsPlant outdoors · Apr 25 – May 9

PotatoesPlant outdoors · May 2 – May 16

LettuceSow outdoors · Apr 25 – May 9

Carrots, beetsSow outdoors · May 2 – May 16

TomatoesStart indoors · Mar 28 – Apr 11

TomatoesTransplant · May 30 – Jun 13

Peppers, eggplantStart indoors · Mar 14 – Mar 28

Peppers, eggplantTransplant · Jun 6 – Jun 20

BeansSow outdoors · May 30 – Jun 13

Sweet cornSow outdoors · May 30 – Jun 13

Cucumbers, squashSow outdoors · May 30 – Jun 13

Fall lettuce, spinachSow outdoors · Jul 22 – Aug 5

GarlicPlant cloves · Sep 2 – Oct 7

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 23) and first fall frost (Sep 16) 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 59474 came on Mar 23 — 25 days earlier than the 1991–2020 average (Apr 17).

average
Apr 172026
Mar 23

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.

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 Shelby, MT.

Soil in Shelby, MT

The soil mapped at the center of ZIP 59474 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 59474; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Shelby, MT

Summer high82 °Faverage high, July

Winter low6 °Faverage low, January

Hot days18days a year at 90 °F or more

Freezing nights190nights a year at 32 °F or less

Growing degree days1,697base 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)

Precipitation12.1 inper year, rain and melted snow

Snowfall39 inper year; 51 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Shelby, MT (7 mi away); precipitation: Shelby, MT (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4a.

Montana planting zones →

Questions about 59474

What planting zone is ZIP code 59474?

ZIP code 59474 (Shelby, 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 Shelby, MT?

The median last spring frost (32 °F) near 59474 is May 23; after June 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Shelby station.

When is the first frost in Shelby, MT?

The median first fall frost near 59474 is September 16, giving a median frost-free growing season of 115 days.

When should I plant tomatoes in 59474?

Start tomato seeds indoors around Mar 28 – Apr 11 and set transplants outside around May 30 – Jun 13, one to three weeks after the median last frost.

How much rain and snow does 59474 get?

About 12.1 inches of precipitation a year and 39 inches of snowfall (NOAA 1991–2020 normals, Shelby station).

How hot do summers get in Shelby, MT?

The average high peaks at 82 °F in July, with about 18 days a year at 90 °F or more.

What kind of soil does 59474 have?

The USDA soil survey maps Scobey at the center of ZIP 59474: clay loam, well drained, pH about 7.0 (neutral).

Did spring come early in Shelby, MT in 2026?

Spring leaf-out near 59474 came on Mar 23 in 2026, 25 days earlier than the 1991–2020 average (Apr 17), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Shelby, MT?

Long-day onions: the longest day near 59474 is 16 h 08 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).