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

Planting zone for 59273 — Vandalia, MT

ZIP code 59273 (Vandalia, Valley County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 15 and the first fall frost September 26.

Where ZIP 59273 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 15

First frostSep 26

2012 zone3b

Was 3b 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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Vandalia, 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 Vandalia, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 15median — 50% chance of a later frost

Safe for tender plantsMay 30only 10% chance of frost after

First fall frostSeptember 26median — 10% chance by Sep 12

Growing season132 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 5 and returns around October 4.

From the NOAA station Hinsdale 4 Sw, MT — 10 miles away, elevation 2,805 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 59273

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 3 – Apr 17

SpinachSow outdoors · Apr 3 – Apr 24

Broccoli, cabbageStart indoors · Mar 6 – Mar 20

Broccoli, cabbageTransplant · Apr 24 – May 8

Onion setsPlant outdoors · Apr 17 – May 1

PotatoesPlant outdoors · Apr 24 – May 8

LettuceSow outdoors · Apr 17 – May 1

Carrots, beetsSow outdoors · Apr 24 – May 8

TomatoesStart indoors · Mar 20 – Apr 3

TomatoesTransplant · May 22 – Jun 5

Peppers, eggplantStart indoors · Mar 6 – Mar 20

Peppers, eggplantTransplant · May 29 – Jun 12

BeansSow outdoors · May 22 – Jun 5

Sweet cornSow outdoors · May 22 – Jun 5

Cucumbers, squashSow outdoors · May 22 – Jun 5

Fall lettuce, spinachSow outdoors · Aug 1 – Aug 15

GarlicPlant cloves · Sep 12 – Oct 17

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 15) and first fall frost (Sep 26) 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 59273 came on Apr 8 — 8 days earlier than the 1991–2020 average (Apr 16).

average
Apr 162026
Apr 8

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 Vandalia, MT.

Soil in Vandalia, MT

The soil mapped at the center of ZIP 59273 is Phillips — loam, well drained.

TextureLoama good balance for most vegetables

pH6.8neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Phillips-Elloam complex, 2 to 8 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 59273; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Vandalia, MT

Summer high84 °Faverage high, July

Winter low6 °Faverage low, January

Hot days21days a year at 90 °F or more

Freezing nights177nights a year at 32 °F or less

Growing degree days2,118base 50 °F — the season’s usable heat

Longest day16 h 06 mindaylight on June 21

Shortest day8 h 19 mindaylight on December 21

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

Precipitation14.2 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: Hinsdale 4 Sw, MT (10 mi away); precipitation: Glasgow 14 Nw, MT (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Saint Marie, MT · 19 mi

Fort Peck, MT · 44 mi

Montana planting zones →

Questions about 59273

What planting zone is ZIP code 59273?

ZIP code 59273 (Vandalia, 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 Vandalia, MT?

The median last spring frost (32 °F) near 59273 is May 15; after May 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Hinsdale 4 Sw station.

When is the first frost in Vandalia, MT?

The median first fall frost near 59273 is September 26, giving a median frost-free growing season of 132 days.

When should I plant tomatoes in 59273?

Start tomato seeds indoors around Mar 20 – Apr 3 and set transplants outside around May 22 – Jun 5, one to three weeks after the median last frost.

How much rain and snow does 59273 get?

About 14.2 inches of precipitation a year (NOAA 1991–2020 normals, Glasgow 14 Nw station).

How hot do summers get in Vandalia, MT?

The average high peaks at 84 °F in July, with about 21 days a year at 90 °F or more.

What kind of soil does 59273 have?

The USDA soil survey maps Phillips at the center of ZIP 59273: loam, well drained, pH about 6.8 (neutral).

Did spring come early in Vandalia, MT in 2026?

Spring leaf-out near 59273 came on Apr 8 in 2026, 8 days earlier than the 1991–2020 average (Apr 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Vandalia, MT?

Long-day onions: the longest day near 59273 is 16 h 06 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59273 change?

Yes. The 2012 USDA map put 59273 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.