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

Planting zone for 59075 — Saint Xavier, MT

ZIP code 59075 (Saint Xavier, Big Horn County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 7 and the first fall frost October 5.

Where ZIP 59075 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 7
First frostOct 5
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 Saint Xavier, 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 Saint Xavier, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 7median — 50% chance of a later frost
Safe for tender plantsMay 24only 10% chance of frost after
First fall frostOctober 5median — 10% chance by Sep 20
Growing season151 daysfrost-free, median

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

From the NOAA station Yellowtail Dam, MT — 8 miles away, elevation 3,304 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 59075

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 26 – Apr 9
SpinachSow outdoors · Mar 26 – Apr 16
Broccoli, cabbageStart indoors · Feb 26 – Mar 12
Broccoli, cabbageTransplant · Apr 16 – Apr 30
Onion setsPlant outdoors · Apr 9 – Apr 23
PotatoesPlant outdoors · Apr 16 – Apr 30
LettuceSow outdoors · Apr 9 – Apr 23
Carrots, beetsSow outdoors · Apr 16 – Apr 30
TomatoesStart indoors · Mar 12 – Mar 26
TomatoesTransplant · May 14 – May 28
Peppers, eggplantStart indoors · Feb 26 – Mar 12
Peppers, eggplantTransplant · May 21 – Jun 4
BeansSow outdoors · May 14 – May 28
Sweet cornSow outdoors · May 14 – May 28
Cucumbers, squashSow outdoors · May 14 – May 28
Fall lettuce, spinachSow outdoors · Aug 10 – Aug 24
GarlicPlant cloves · Sep 21 – Oct 26
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 7) and first fall frost (Oct 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 59075 came on Mar 3 — 27 days earlier than the 1991–2020 average (Mar 30).

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 Saint Xavier, MT.

Soil in Saint Xavier, MT

The soil mapped at the center of ZIP 59075 is Colby — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH7.5slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classFarmland of statewide importanceUSDA classification

Map unit: Colby silt loam, 4 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 59075; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Xavier, MT

Summer high89 °Faverage high, July
Winter low20 °Faverage low, January
Hot days45days a year at 90 °F or more
Freezing nights126nights a year at 32 °F or less
Growing degree days2,762base 50 °F — the season’s usable heat
Longest day15 h 40 mindaylight on June 21
Shortest day8 h 43 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation16.7 inper year, rain and melted snow
Snowfall44 inper year

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 39 °F, low 20 °F 39°20° JanFebruary: average high 40 °F, low 21 °F 40°21° FebMarch: average high 50 °F, low 28 °F 50°28° MarApril: average high 58 °F, low 36 °F 58°36° AprMay: average high 68 °F, low 44 °F 68°44° MayJune: average high 78 °F, low 53 °F 78°53° JunJuly: average high 89 °F, low 59 °F 89°59° JulAugust: average high 87 °F, low 57 °F 87°57° AugSeptember: average high 76 °F, low 49 °F 76°49° SepOctober: average high 61 °F, low 38 °F 61°38° OctNovember: average high 48 °F, low 28 °F 48°28° NovDecember: average high 39 °F, low 21 °F 39°21° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.72 in precipitation, 8.8 in snowfall 0.7❄9 JanFebruary: 0.83 in precipitation, 7.4 in snowfall 0.8❄7 FebMarch: 1.21 in precipitation, 8.4 in snowfall 1.2❄8 MarApril: 1.95 in precipitation, 3 in snowfall 1.9❄3 AprMay: 2.62 in precipitation, 0.2 in snowfall 2.6 MayJune: 2.27 in precipitation 2.3 JunJuly: 1.15 in precipitation 1.1 JulAugust: 0.78 in precipitation 0.8 AugSeptember: 1.67 in precipitation 1.7 SepOctober: 1.98 in precipitation, 3 in snowfall 2.0❄3 OctNovember: 0.77 in precipitation, 5.8 in snowfall 0.8❄6 NovDecember: 0.72 in precipitation, 7.3 in snowfall 0.7❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Yellowtail Dam, MT (8 mi away); precipitation: Yellowtail Dam, MT (8 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.

590355a
Fort Smith, MT · 9 mi
590344b
Hardin, MT · 21 mi
590505a
Lodge Grass, MT · 21 mi
590314b
Garryowen, MT · 24 mi
591015a
Billings, MT · 28 mi
590224b
Crow Agency, MT · 31 mi
590644b
Pompeys Pillar, MT · 33 mi
590894b
Wyola, MT · 34 mi

Montana planting zones →

Questions about 59075

What planting zone is ZIP code 59075?

ZIP code 59075 (Saint Xavier, 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 Saint Xavier, MT?

The median last spring frost (32 °F) near 59075 is May 7; after May 24 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Yellowtail Dam station.

When is the first frost in Saint Xavier, MT?

The median first fall frost near 59075 is October 5, giving a median frost-free growing season of 151 days.

When should I plant tomatoes in 59075?

Start tomato seeds indoors around Mar 12 – Mar 26 and set transplants outside around May 14 – May 28, one to three weeks after the median last frost.

How much rain and snow does 59075 get?

About 16.7 inches of precipitation a year and 44 inches of snowfall (NOAA 1991–2020 normals, Yellowtail Dam station).

How hot do summers get in Saint Xavier, MT?

The average high peaks at 89 °F in July, with about 45 days a year at 90 °F or more.

What kind of soil does 59075 have?

The USDA soil survey maps Colby at the center of ZIP 59075: silt loam, well drained, pH about 7.5 (slightly alkaline).

Did spring come early in Saint Xavier, MT in 2026?

Spring leaf-out near 59075 came on Mar 3 in 2026, 27 days earlier than the 1991–2020 average (Mar 30), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint Xavier, MT?

Long-day onions: the longest day near 59075 is 15 h 40 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).