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

Planting zone for 59912 — Columbia Falls, MT

ZIP code 59912 (Columbia Falls, Flathead County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 16 and the first fall frost September 25.

Where ZIP 59912 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 frostMay 16
First frostSep 25
2012 zone5a

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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Columbia Falls, 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 Columbia Falls, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 16median — 50% chance of a later frost
Safe for tender plantsJune 6only 10% chance of frost after
First fall frostSeptember 25median — 10% chance by Sep 8
Growing season129 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 1 and returns around October 7.

From the NOAA station Whitefish, MT — 9 miles away, elevation 3,101 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 59912

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 4 – Apr 18
SpinachSow outdoors · Apr 4 – Apr 25
Broccoli, cabbageStart indoors · Mar 7 – Mar 21
Broccoli, cabbageTransplant · Apr 25 – May 9
Onion setsPlant outdoors · Apr 18 – May 2
PotatoesPlant outdoors · Apr 25 – May 9
LettuceSow outdoors · Apr 18 – May 2
Carrots, beetsSow outdoors · Apr 25 – May 9
TomatoesStart indoors · Mar 21 – Apr 4
TomatoesTransplant · May 23 – Jun 6
Peppers, eggplantStart indoors · Mar 7 – Mar 21
Peppers, eggplantTransplant · May 30 – Jun 13
BeansSow outdoors · May 23 – Jun 6
Sweet cornSow outdoors · May 23 – Jun 6
Cucumbers, squashSow outdoors · May 23 – Jun 6
Fall lettuce, spinachSow outdoors · Jul 31 – Aug 14
GarlicPlant cloves · Sep 11 – Oct 16
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 16) and first fall frost (Sep 25) 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 59912 came on Apr 13 — 10 days earlier than the 1991–2020 average (Apr 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 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.

Trees 26

American elm120 ft · blooms early spring · medium shade tolerance · to −46 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °FDouglas-fir200 ft · blooms mid spring · medium shade tolerance · to −33 °Feastern cottonwood190 ft · blooms spring · high shade tolerance · to −43 °F

Shrubs 96

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °F

Wildflowers & perennials 253

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °F

Grasses 161

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Fanalogue sedge1.5 ft · blooms late spring · medium shade tolerance · to −38 °F

Vines 3

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °F

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 Columbia Falls, MT.

Soil in Columbia Falls, MT

The soil mapped at the center of ZIP 59912 is Dystric Eutrochrepts — slightly decomposed plant material.

TextureSlightly decomposed plant materialtop layer
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Dystric Eutrochrepts, till substratum.

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 59912; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Columbia Falls, MT

Summer high81 °Faverage high, July
Winter low16 °Faverage low, January
Hot days13days a year at 90 °F or more
Freezing nights195nights a year at 32 °F or less
Growing degree days1,456base 50 °F — the season’s usable heat
Longest day16 h 07 mindaylight on June 21
Shortest day8 h 18 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation19.9 inper year, rain and melted snow
Snowfall63 inper year; 124 days with snow on the ground

Average high and low, by month

10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 29 °F, low 16 °F 29°16° JanFebruary: average high 34 °F, low 16 °F 34°16° FebMarch: average high 43 °F, low 23 °F 43°23° MarApril: average high 53 °F, low 30 °F 53°30° AprMay: average high 64 °F, low 39 °F 64°39° MayJune: average high 70 °F, low 45 °F 70°45° JunJuly: average high 81 °F, low 50 °F 81°50° JulAugust: average high 80 °F, low 48 °F 80°48° AugSeptember: average high 69 °F, low 40 °F 69°40° SepOctober: average high 53 °F, low 31 °F 53°31° OctNovember: average high 38 °F, low 24 °F 38°24° NovDecember: average high 29 °F, low 18 °F 29°18° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 1.84 in precipitation, 16.5 in snowfall 1.8❄17 JanFebruary: 1.26 in precipitation, 7 in snowfall 1.3❄7 FebMarch: 1.27 in precipitation, 8 in snowfall 1.3❄8 MarApril: 1.61 in precipitation, 1.6 in snowfall 1.6❄2 AprMay: 1.99 in precipitation, 0.1 in snowfall 2.0 MayJune: 3.20 in precipitation 3.2 JunJuly: 1.40 in precipitation 1.4 JulAugust: 0.89 in precipitation 0.9 AugSeptember: 1.25 in precipitation 1.3 SepOctober: 1.45 in precipitation, 0.4 in snowfall 1.4 OctNovember: 1.70 in precipitation, 8.3 in snowfall 1.7❄8 NovDecember: 2.07 in precipitation, 21.2 in snowfall 2.1❄21 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Whitefish, MT (9 mi away); precipitation: Whitefish, MT (9 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.

599195b
Hungry Horse, MT · 7 mi
599135a
Coram, MT · 10 mi
599265b
Martin City, MT · 10 mi
599215a
Lake Mc Donald, MT · 14 mi
599045b
Kalispell, MT · 14 mi
599375a
Whitefish, MT · 15 mi
599015b
Kalispell, MT · 18 mi
599035b
Kalispell, MT · 19 mi

Montana planting zones →

Questions about 59912

What planting zone is ZIP code 59912?

ZIP code 59912 (Columbia Falls, 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 Columbia Falls, MT?

The median last spring frost (32 °F) near 59912 is May 16; after June 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Whitefish station.

When is the first frost in Columbia Falls, MT?

The median first fall frost near 59912 is September 25, giving a median frost-free growing season of 129 days.

When should I plant tomatoes in 59912?

Start tomato seeds indoors around Mar 21 – Apr 4 and set transplants outside around May 23 – Jun 6, one to three weeks after the median last frost.

How much rain and snow does 59912 get?

About 19.9 inches of precipitation a year and 63 inches of snowfall (NOAA 1991–2020 normals, Whitefish station).

How hot do summers get in Columbia Falls, MT?

The average high peaks at 81 °F in July, with about 13 days a year at 90 °F or more.

What kind of soil does 59912 have?

The USDA soil survey maps Dystric Eutrochrepts at the center of ZIP 59912: slightly decomposed plant material.

Did spring come early in Columbia Falls, MT in 2026?

Spring leaf-out near 59912 came on Apr 13 in 2026, 10 days earlier than the 1991–2020 average (Apr 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Columbia Falls, MT?

Long-day onions: the longest day near 59912 is 16 h 07 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).