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

Planting zone for 59432 — Dupuyer, MT

ZIP code 59432 (Dupuyer, Pondera County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is June 9 and the first fall frost September 3.

Where ZIP 59432 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 frostJun 9

First frostSep 3

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 Dupuyer, 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 Dupuyer, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 9median — 50% chance of a later frost

Safe for tender plantsJuly 2only 10% chance of frost after

First fall frostSeptember 3median — 10% chance by Aug 19

Growing season86 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 23 and returns around September 17.

From the NOAA station Blackleaf, MT — 11 miles away, elevation 4,236 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 59432

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 28 – May 12

SpinachSow outdoors · Apr 28 – May 19

Broccoli, cabbageStart indoors · Mar 31 – Apr 14

Broccoli, cabbageTransplant · May 19 – Jun 2

Onion setsPlant outdoors · May 12 – May 26

PotatoesPlant outdoors · May 19 – Jun 2

LettuceSow outdoors · May 12 – May 26

Carrots, beetsSow outdoors · May 19 – Jun 2

TomatoesStart indoors · Apr 14 – Apr 28

TomatoesTransplant · Jun 16 – Jun 30

Peppers, eggplantStart indoors · Mar 31 – Apr 14

Peppers, eggplantTransplant · Jun 23 – Jul 7

BeansSow outdoors · Jun 16 – Jun 30

Sweet cornSow outdoors · Jun 16 – Jun 30

Cucumbers, squashSow outdoors · Jun 16 – Jun 30

Fall lettuce, spinachSow outdoors · Jul 9 – Jul 23

GarlicPlant cloves · Aug 20 – Sep 24

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 9) and first fall frost (Sep 3) 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 59432 came on Mar 23 — 30 days earlier than the 1991–2020 average (Apr 22).

average
Apr 222026
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 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.

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 Dupuyer, MT.

Soil in Dupuyer, MT

The soil mapped at the center of ZIP 59432 is Kiev — loam, well drained.

TextureLoama good balance for most vegetables

pH7.2neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Kiev-Roundor-Windham complex, 15 to 45 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 59432; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Dupuyer, MT

Summer high80 °Faverage high, July

Winter low9 °Faverage low, January

Hot days10days a year at 90 °F or more

Freezing nights207nights a year at 32 °F or less

Growing degree days1,224base 50 °F — the season’s usable heat

Longest day16 h 04 mindaylight on June 21

Shortest day8 h 21 mindaylight on December 21

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

Precipitation29.3 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: Blackleaf, MT (11 mi away); precipitation: Dupuyer Creek, MT (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Heart Butte, MT · 16 mi

Montana planting zones →

Questions about 59432

What planting zone is ZIP code 59432?

ZIP code 59432 (Dupuyer, 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 Dupuyer, MT?

The median last spring frost (32 °F) near 59432 is June 9; after July 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Blackleaf station.

When is the first frost in Dupuyer, MT?

The median first fall frost near 59432 is September 3, giving a median frost-free growing season of 86 days.

When should I plant tomatoes in 59432?

Start tomato seeds indoors around Apr 14 – Apr 28 and set transplants outside around Jun 16 – Jun 30, one to three weeks after the median last frost.

How much rain and snow does 59432 get?

About 29.3 inches of precipitation a year (NOAA 1991–2020 normals, Dupuyer Creek station).

How hot do summers get in Dupuyer, MT?

The average high peaks at 80 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 59432 have?

The USDA soil survey maps Kiev at the center of ZIP 59432: loam, well drained, pH about 7.2 (neutral).

Did spring come early in Dupuyer, MT in 2026?

Spring leaf-out near 59432 came on Mar 23 in 2026, 30 days earlier than the 1991–2020 average (Apr 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Dupuyer, MT?

Long-day onions: the longest day near 59432 is 16 h 04 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59432 change?

Yes. The 2012 USDA map put 59432 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.