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

Planting zone for 59240 — Glentana, MT

ZIP code 59240 (Glentana, Valley County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is June 5 and the first fall frost September 2.

Where ZIP 59240 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.

Zone3b−35 to −30 °F

Coldest night−37.2 to −34.4 °C

Last frostJun 5

First frostSep 2

2012 zone3b

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 3b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Glentana, 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 Glentana, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 5median — 50% chance of a later frost

Safe for tender plantsJune 23only 10% chance of frost after

First fall frostSeptember 2median — 10% chance by Aug 15

Growing season89 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 24 and returns around September 14.

From the NOAA station Opheim 12 Sse, MT — 11 miles away, elevation 2,936 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 59240

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 24 – May 8

SpinachSow outdoors · Apr 24 – May 15

Broccoli, cabbageStart indoors · Mar 27 – Apr 10

Broccoli, cabbageTransplant · May 15 – May 29

Onion setsPlant outdoors · May 8 – May 22

PotatoesPlant outdoors · May 15 – May 29

LettuceSow outdoors · May 8 – May 22

Carrots, beetsSow outdoors · May 15 – May 29

TomatoesStart indoors · Apr 10 – Apr 24

TomatoesTransplant · Jun 12 – Jun 26

Peppers, eggplantStart indoors · Mar 27 – Apr 10

Peppers, eggplantTransplant · Jun 19 – Jul 3

BeansSow outdoors · Jun 12 – Jun 26

Sweet cornSow outdoors · Jun 12 – Jun 26

Cucumbers, squashSow outdoors · Jun 12 – Jun 26

Fall lettuce, spinachSow outdoors · Jul 8 – Jul 22

GarlicPlant cloves · Aug 19 – Sep 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 5) and first fall frost (Sep 2) 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 59240 came on Apr 28 — 3 days later than the 1991–2020 average (Apr 25).

average
Apr 252026
Apr 28

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 3b in Montana

304 plants native to the lower 48 states, recorded in Montana, and rated by the USDA to survive −35 °F or colder — the bottom of zone 3b. 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 Glentana, MT.

Soil in Glentana, MT

The soil mapped at the center of ZIP 59240 is Farnuf — loam, well drained.

TextureLoama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Farnuf-Tinsley-Reeder association, hilly.

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 59240; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Glentana, MT

Summer high77 °Faverage high, July

Winter low−3 °Faverage low, January

Hot days9days a year at 90 °F or more

Freezing nights217nights a year at 32 °F or less

Growing degree days1,153base 50 °F — the season’s usable heat

Longest day16 h 11 mindaylight on June 21

Shortest day8 h 15 mindaylight on December 21

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

Precipitation12.3 inper year, rain and melted snow

Snowfall39 inper year; 102 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: Opheim 12 Sse, MT (11 mi away); precipitation: Opheim 12 Sse, MT (11 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.

Saint Marie, MT · 33 mi

Montana planting zones →

Questions about 59240

What planting zone is ZIP code 59240?

ZIP code 59240 (Glentana, MT) is in USDA hardiness zone 3b on the 2023 map: the coldest night of an average winter reaches −35 to −30 °F (−37.2 to −34.4 °C).

When is the last frost in Glentana, MT?

The median last spring frost (32 °F) near 59240 is June 5; after June 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Opheim 12 Sse station.

When is the first frost in Glentana, MT?

The median first fall frost near 59240 is September 2, giving a median frost-free growing season of 89 days.

When should I plant tomatoes in 59240?

Start tomato seeds indoors around Apr 10 – Apr 24 and set transplants outside around Jun 12 – Jun 26, one to three weeks after the median last frost.

How much rain and snow does 59240 get?

About 12.3 inches of precipitation a year and 39 inches of snowfall (NOAA 1991–2020 normals, Opheim 12 Sse station).

How hot do summers get in Glentana, MT?

The average high peaks at 77 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 59240 have?

The USDA soil survey maps Farnuf at the center of ZIP 59240: loam, well drained, pH about 7.0 (neutral).

Did spring come early in Glentana, MT in 2026?

Spring leaf-out near 59240 came on Apr 28 in 2026, 3 days later than the 1991–2020 average (Apr 25), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Glentana, MT?

Long-day onions: the longest day near 59240 is 16 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).