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

Planting zone for 59871 — Sula, MT

ZIP code 59871 (Sula, Ravalli County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 24 and the first fall frost September 23.

Where ZIP 59871 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 24
First frostSep 23
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 Sula, 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 Sula, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 24median — 50% chance of a later frost
Safe for tender plantsJune 14only 10% chance of frost after
First fall frostSeptember 23median — 10% chance by Sep 4
Growing season118 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 5 and returns around October 4.

From the NOAA station Darby, MT — 20 miles away, elevation 3,881 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 59871

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 12 – Apr 26
SpinachSow outdoors · Apr 12 – May 3
Broccoli, cabbageStart indoors · Mar 15 – Mar 29
Broccoli, cabbageTransplant · May 3 – May 17
Onion setsPlant outdoors · Apr 26 – May 10
PotatoesPlant outdoors · May 3 – May 17
LettuceSow outdoors · Apr 26 – May 10
Carrots, beetsSow outdoors · May 3 – May 17
TomatoesStart indoors · Mar 29 – Apr 12
TomatoesTransplant · May 31 – Jun 14
Peppers, eggplantStart indoors · Mar 15 – Mar 29
Peppers, eggplantTransplant · Jun 7 – Jun 21
BeansSow outdoors · May 31 – Jun 14
Sweet cornSow outdoors · May 31 – Jun 14
Cucumbers, squashSow outdoors · May 31 – Jun 14
Fall lettuce, spinachSow outdoors · Jul 29 – Aug 12
GarlicPlant cloves · Sep 9 – Oct 14
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 24) and first fall frost (Sep 23) 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 59871 came on Apr 18 — 18 days earlier than the 1991–2020 average (May 6).

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 Sula, MT.

Soil in Sula, MT

The soil mapped at the center of ZIP 59871 is Leighcan — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer
pH5.5moderately acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter75%high
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Leighcan family, steep mountain slopes, moist.

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 59871; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sula, MT

Summer high81 °Faverage high, July
Winter low10 °Faverage low, January
Hot days12days a year at 90 °F or more
Freezing nights255nights a year at 32 °F or less
Growing degree days943base 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)
Precipitation20.8 inper year, rain and melted snow
Snowfall88 inper year; 147 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 32 °F, low 10 °F 32°10° JanFebruary: average high 36 °F, low 12 °F 36°12° FebMarch: average high 43 °F, low 20 °F 43°20° MarApril: average high 50 °F, low 25 °F 50°25° AprMay: average high 61 °F, low 32 °F 61°32° MayJune: average high 70 °F, low 37 °F 70°37° JunJuly: average high 81 °F, low 40 °F 81°40° JulAugust: average high 81 °F, low 38 °F 81°38° AugSeptember: average high 70 °F, low 32 °F 70°32° SepOctober: average high 54 °F, low 26 °F 54°26° OctNovember: average high 38 °F, low 18 °F 38°18° NovDecember: average high 29 °F, low 10 °F 29°10° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 1.52 in precipitation, 15.8 in snowfall 1.5❄16 JanFebruary: 1.38 in precipitation, 17 in snowfall 1.4❄17 FebMarch: 1.73 in precipitation, 14.3 in snowfall 1.7❄14 MarApril: 1.72 in precipitation, 6.3 in snowfall 1.7❄6 AprMay: 2.57 in precipitation, 2 in snowfall 2.6❄2 MayJune: 2.87 in precipitation, 0.9 in snowfall 2.9❄1 JunJuly: 1.27 in precipitation 1.3 JulAugust: 1.08 in precipitation 1.1 AugSeptember: 1.62 in precipitation, 0.4 in snowfall 1.6 SepOctober: 1.48 in precipitation, 2.4 in snowfall 1.5❄2 OctNovember: 1.77 in precipitation, 10.3 in snowfall 1.8❄10 NovDecember: 1.81 in precipitation, 19 in snowfall 1.8❄19 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Sula 14 Ne, MT (4 mi away); precipitation: Sula 14 Ne, MT (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

598275b
Conner, MT · 13 mi
598295b
Darby, MT · 20 mi
598405b
Hamilton, MT · 23 mi
597625a
Wise River, MT · 24 mi
834635b
Gibbonsville, ID · 24 mi
597615a
Wisdom, MT · 25 mi
598355b
Grantsdale, MT · 27 mi
598285b
Corvallis, MT · 31 mi

Montana planting zones →

Questions about 59871

What planting zone is ZIP code 59871?

ZIP code 59871 (Sula, 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 Sula, MT?

The median last spring frost (32 °F) near 59871 is May 24; after June 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Darby station.

When is the first frost in Sula, MT?

The median first fall frost near 59871 is September 23, giving a median frost-free growing season of 118 days.

When should I plant tomatoes in 59871?

Start tomato seeds indoors around Mar 29 – Apr 12 and set transplants outside around May 31 – Jun 14, one to three weeks after the median last frost.

How much rain and snow does 59871 get?

About 20.8 inches of precipitation a year and 88 inches of snowfall (NOAA 1991–2020 normals, Sula 14 Ne station).

How hot do summers get in Sula, MT?

The average high peaks at 81 °F in July, with about 12 days a year at 90 °F or more.

What kind of soil does 59871 have?

The USDA soil survey maps Leighcan at the center of ZIP 59871: slightly decomposed plant material, well drained, pH about 5.5 (moderately acidic).

Did spring come early in Sula, MT in 2026?

Spring leaf-out near 59871 came on Apr 18 in 2026, 18 days earlier than the 1991–2020 average (May 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sula, MT?

Long-day onions: the longest day near 59871 is 15 h 44 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).