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

Planting zone for 59015 — Broadview, MT

ZIP code 59015 (Broadview, Yellowstone County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 22 and the first fall frost September 15.

Where ZIP 59015 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 22

First frostSep 15

2012 zone4b

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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Broadview, 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 Broadview, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 22median — 50% chance of a later frost

Safe for tender plantsJune 4only 10% chance of frost after

First fall frostSeptember 15median — 10% chance by Aug 31

Growing season114 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 11 and returns around September 26.

From the NOAA station Roundup 15 Sw, MT — 17 miles away, elevation 3,386 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 59015

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 10 – Apr 24

SpinachSow outdoors · Apr 10 – May 1

Broccoli, cabbageStart indoors · Mar 13 – Mar 27

Broccoli, cabbageTransplant · May 1 – May 15

Onion setsPlant outdoors · Apr 24 – May 8

PotatoesPlant outdoors · May 1 – May 15

LettuceSow outdoors · Apr 24 – May 8

Carrots, beetsSow outdoors · May 1 – May 15

TomatoesStart indoors · Mar 27 – Apr 10

TomatoesTransplant · May 29 – Jun 12

Peppers, eggplantStart indoors · Mar 13 – Mar 27

Peppers, eggplantTransplant · Jun 5 – Jun 19

BeansSow outdoors · May 29 – Jun 12

Sweet cornSow outdoors · May 29 – Jun 12

Cucumbers, squashSow outdoors · May 29 – Jun 12

Fall lettuce, spinachSow outdoors · Jul 21 – Aug 4

GarlicPlant cloves · Sep 1 – Oct 6

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 22) and first fall frost (Sep 15) 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 59015 came on Mar 9 — 29 days earlier than the 1991–2020 average (Apr 7).

average
Apr 72026
Mar 9

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 Broadview, MT.

Soil in Broadview, MT

The soil mapped at the center of ZIP 59015 is Vananda — silty clay, well drained.

TextureSilty clayholds water and nutrients; slow to drain and warm up

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Vananda silty clay, 0 to 1 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 59015; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Broadview, MT

Summer high87 °Faverage high, July

Winter low11 °Faverage low, January

Hot days41days a year at 90 °F or more

Freezing nights196nights a year at 32 °F or less

Growing degree days1,891base 50 °F — the season’s usable heat

Longest day15 h 46 mindaylight on June 21

Shortest day8 h 38 mindaylight on December 21

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

Precipitation15.1 inper year, rain and melted snow

Snowfall43 inper year; 57 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: Roundup 15 Sw, MT (17 mi away); precipitation: Roundup 15 Sw, MT (17 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Montana planting zones →

Questions about 59015

What planting zone is ZIP code 59015?

ZIP code 59015 (Broadview, 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 Broadview, MT?

The median last spring frost (32 °F) near 59015 is May 22; after June 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Roundup 15 Sw station.

When is the first frost in Broadview, MT?

The median first fall frost near 59015 is September 15, giving a median frost-free growing season of 114 days.

When should I plant tomatoes in 59015?

Start tomato seeds indoors around Mar 27 – Apr 10 and set transplants outside around May 29 – Jun 12, one to three weeks after the median last frost.

How much rain and snow does 59015 get?

About 15.1 inches of precipitation a year and 43 inches of snowfall (NOAA 1991–2020 normals, Roundup 15 Sw station).

How hot do summers get in Broadview, MT?

The average high peaks at 87 °F in July, with about 41 days a year at 90 °F or more.

What kind of soil does 59015 have?

The USDA soil survey maps Vananda at the center of ZIP 59015: silty clay, well drained, pH about 8.2 (alkaline).

Did spring come early in Broadview, MT in 2026?

Spring leaf-out near 59015 came on Mar 9 in 2026, 29 days earlier than the 1991–2020 average (Apr 7), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Broadview, MT?

Long-day onions: the longest day near 59015 is 15 h 46 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).