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

Planting zone for 59759 — Whitehall, MT

ZIP code 59759 (Whitehall, Jefferson County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is June 13 and the first fall frost September 5.

Where ZIP 59759 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.

Zone5a−20 to −15 °F

Coldest night−28.9 to −26.1 °C

Last frostJun 13

First frostSep 5

2012 zone4b

Was 4b 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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Whitehall, 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 Whitehall, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 13median — 50% chance of a later frost

Safe for tender plantsJuly 1only 10% chance of frost after

First fall frostSeptember 5median — 10% chance by Aug 24

Growing season83 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 21 and returns around September 17.

From the NOAA station Butte Bert Mooney Airport, MT — 18 miles away, elevation 5,506 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 59759

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 2 – May 16

SpinachSow outdoors · May 2 – May 23

Broccoli, cabbageStart indoors · Apr 4 – Apr 18

Broccoli, cabbageTransplant · May 23 – Jun 6

Onion setsPlant outdoors · May 16 – May 30

PotatoesPlant outdoors · May 23 – Jun 6

LettuceSow outdoors · May 16 – May 30

Carrots, beetsSow outdoors · May 23 – Jun 6

TomatoesStart indoors · Apr 18 – May 2

TomatoesTransplant · Jun 20 – Jul 4

Peppers, eggplantStart indoors · Apr 4 – Apr 18

Peppers, eggplantTransplant · Jun 27 – Jul 11

BeansSow outdoors · Jun 20 – Jul 4

Sweet cornSow outdoors · Jun 20 – Jul 4

Cucumbers, squashSow outdoors · Jun 20 – Jul 4

Fall lettuce, spinachSow outdoors · Jul 11 – Jul 25

GarlicPlant cloves · Aug 22 – Sep 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 13) and first fall frost (Sep 5) 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 59759 came on Mar 13 — 30 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
Mar 13

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 5a in Montana

548 plants native to the lower 48 states, recorded in Montana, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. 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 Whitehall, MT.

Soil in Whitehall, MT

The soil mapped at the center of ZIP 59759 is Sappington — clay loam, well drained.

TextureClay loamholds water and nutrients; slow to drain and warm up

pH7.2neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of local importanceUSDA classification

Map unit: Sappington clay loam, 8 to 15 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 59759; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Whitehall, MT

Summer high81 °Faverage high, July

Winter low7 °Faverage low, December

Hot days8days a year at 90 °F or more

Freezing nights220nights a year at 32 °F or less

Growing degree days1,210base 50 °F — the season’s usable heat

Longest day15 h 44 mindaylight on June 21

Shortest day8 h 39 mindaylight on December 21

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

Precipitation24.1 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: Butte Bert Mooney Airport, MT (18 mi away); precipitation: Basin Creek, MT (17 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.

597515a

Silver Star, MT · 12 mi

Montana planting zones →

Questions about 59759

What planting zone is ZIP code 59759?

ZIP code 59759 (Whitehall, MT) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Whitehall, MT?

The median last spring frost (32 °F) near 59759 is June 13; after July 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Butte Bert Mooney Airport station.

When is the first frost in Whitehall, MT?

The median first fall frost near 59759 is September 5, giving a median frost-free growing season of 83 days.

When should I plant tomatoes in 59759?

Start tomato seeds indoors around Apr 18 – May 2 and set transplants outside around Jun 20 – Jul 4, one to three weeks after the median last frost.

How much rain and snow does 59759 get?

About 24.1 inches of precipitation a year (NOAA 1991–2020 normals, Basin Creek station).

How hot do summers get in Whitehall, MT?

The average high peaks at 81 °F in July, with about 8 days a year at 90 °F or more.

What kind of soil does 59759 have?

The USDA soil survey maps Sappington at the center of ZIP 59759: clay loam, well drained, pH about 7.2 (neutral).

Did spring come early in Whitehall, MT in 2026?

Spring leaf-out near 59759 came on Mar 13 in 2026, 30 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Whitehall, MT?

Long-day onions: the longest day near 59759 is 15 h 44 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59759 change?

Yes. The 2012 USDA map put 59759 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.