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

Planting zone for 59405 — Great Falls, MT

ZIP code 59405 (Great Falls, Cascade County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 12 and the first fall frost September 28.

Where ZIP 59405 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 12
First frostSep 28
2012 zone4a

Was 4a 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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Great 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 Great Falls, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 12median — 50% chance of a later frost
Safe for tender plantsMay 27only 10% chance of frost after
First fall frostSeptember 28median — 10% chance by Sep 14
Growing season138 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 8.

From the NOAA station Great Falls WFO, MT — 12 miles away, elevation 3,704 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 59405

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 31 – Apr 14
SpinachSow outdoors · Mar 31 – Apr 21
Broccoli, cabbageStart indoors · Mar 3 – Mar 17
Broccoli, cabbageTransplant · Apr 21 – May 5
Onion setsPlant outdoors · Apr 14 – Apr 28
PotatoesPlant outdoors · Apr 21 – May 5
LettuceSow outdoors · Apr 14 – Apr 28
Carrots, beetsSow outdoors · Apr 21 – May 5
TomatoesStart indoors · Mar 17 – Mar 31
TomatoesTransplant · May 19 – Jun 2
Peppers, eggplantStart indoors · Mar 3 – Mar 17
Peppers, eggplantTransplant · May 26 – Jun 9
BeansSow outdoors · May 19 – Jun 2
Sweet cornSow outdoors · May 19 – Jun 2
Cucumbers, squashSow outdoors · May 19 – Jun 2
Fall lettuce, spinachSow outdoors · Aug 3 – Aug 17
GarlicPlant cloves · Sep 14 – Oct 19
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 12) and first fall frost (Sep 28) 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 59405 came on Mar 16 — 28 days earlier than the 1991–2020 average (Apr 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 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.

Trees 23

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 87

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 229

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 155

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 Great Falls, MT.

Soil in Great Falls, MT

The soil mapped at the center of ZIP 59405 is Absarokee — loam, well drained.

TextureLoama good balance for most vegetables
pH6.7neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter4.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Absarokee, Borky, and Blythe soils, 15 to 45 percent slo pes.

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 59405; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Great Falls, MT

Summer high83 °Faverage high, July
Winter low16 °Faverage low, January
Hot days20days a year at 90 °F or more
Freezing nights157nights a year at 32 °F or less
Growing degree days1,938base 50 °F — the season’s usable heat
Longest day15 h 56 mindaylight on June 21
Shortest day8 h 28 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation14.6 inper year, rain and melted snow
Snowfall69 inper year; 61 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 35 °F, low 16 °F 35°16° JanFebruary: average high 37 °F, low 17 °F 37°17° FebMarch: average high 46 °F, low 24 °F 46°24° MarApril: average high 54 °F, low 32 °F 54°32° AprMay: average high 64 °F, low 40 °F 64°40° MayJune: average high 72 °F, low 48 °F 72°48° JunJuly: average high 83 °F, low 54 °F 83°54° JulAugust: average high 82 °F, low 52 °F 82°52° AugSeptember: average high 71 °F, low 45 °F 71°45° SepOctober: average high 57 °F, low 35 °F 57°35° OctNovember: average high 44 °F, low 25 °F 44°25° NovDecember: average high 36 °F, low 18 °F 36°18° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.55 in precipitation, 9.5 in snowfall 0.6❄10 JanFebruary: 0.55 in precipitation, 11.5 in snowfall 0.6❄12 FebMarch: 0.67 in precipitation, 9.7 in snowfall 0.7❄10 MarApril: 1.72 in precipitation, 10.7 in snowfall 1.7❄11 AprMay: 2.49 in precipitation, 1.9 in snowfall 2.5❄2 MayJune: 2.78 in precipitation, 0.3 in snowfall 2.8 JunJuly: 1.20 in precipitation 1.2 JulAugust: 1.25 in precipitation 1.3 AugSeptember: 1.32 in precipitation, 1.2 in snowfall 1.3❄1 SepOctober: 1.00 in precipitation, 5.1 in snowfall 1.0❄5 OctNovember: 0.63 in precipitation, 9.3 in snowfall 0.6❄9 NovDecember: 0.48 in precipitation, 9.7 in snowfall 0.5❄10 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Great Falls WFO, MT (12 mi away); precipitation: Great Falls WFO, MT (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

594724b
Sand Coulee, MT · 6 mi
594804b
Stockett, MT · 12 mi
594034b
Great Falls, MT · 15 mi
594014b
Great Falls, MT · 15 mi
594854a
Ulm, MT · 16 mi
594144b
Black Eagle, MT · 17 mi
594064b
Great Falls, MT · 23 mi
594214b
Cascade, MT · 23 mi

All 5 ZIP codes in Great Falls → · Montana planting zones →

Questions about 59405

What planting zone is ZIP code 59405?

ZIP code 59405 (Great Falls, 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 Great Falls, MT?

The median last spring frost (32 °F) near 59405 is May 12; after May 27 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Great Falls WFO station.

When is the first frost in Great Falls, MT?

The median first fall frost near 59405 is September 28, giving a median frost-free growing season of 138 days.

When should I plant tomatoes in 59405?

Start tomato seeds indoors around Mar 17 – Mar 31 and set transplants outside around May 19 – Jun 2, one to three weeks after the median last frost.

How much rain and snow does 59405 get?

About 14.6 inches of precipitation a year and 69 inches of snowfall (NOAA 1991–2020 normals, Great Falls WFO station).

How hot do summers get in Great Falls, MT?

The average high peaks at 83 °F in July, with about 20 days a year at 90 °F or more.

What kind of soil does 59405 have?

The USDA soil survey maps Absarokee at the center of ZIP 59405: loam, well drained, pH about 6.7 (neutral).

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

Spring leaf-out near 59405 came on Mar 16 in 2026, 28 days earlier than the 1991–2020 average (Apr 13), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Great Falls, MT?

Long-day onions: the longest day near 59405 is 15 h 56 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59405 change?

Yes. The 2012 USDA map put 59405 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.