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

Planting zone for Butte, MT

Butte, MT is in USDA zones 4a to 5a across its 5 ZIP codes. The median last spring frost is June 13 and the first fall frost September 5.

Butte on the zone map

Outlined: its 2 ZIP code areas · 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.

Zones4a–5a−30 to −15 °F

ZIP codes5

Last frostJun 13

First frostSep 5

Growing season83 days

4a 2 ZIPs 4b 1 ZIP 5a 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

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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 Butte, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 13median — 50% chance of a later frost

Safe for tender plantsJuly 1only 10% chance of frost after

First fall frostSeptember 5median — 10% chance by Aug 24

Growing season83 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 21 and returns around September 17.

From the NOAA station Butte Bert Mooney Airport, MT, elevation 5,506 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 Butte

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · May 2 – May 16

SpinachSow outdoors · May 2 – May 23

Broccoli, cabbageStart indoors · Apr 4 – Apr 18

Broccoli, cabbageTransplant · May 23 – Jun 6

Onion setsPlant outdoors · May 16 – May 30

PotatoesPlant outdoors · May 23 – Jun 6

LettuceSow outdoors · May 16 – May 30

Carrots, beetsSow outdoors · May 23 – Jun 6

TomatoesStart indoors · Apr 18 – May 2

TomatoesTransplant · Jun 20 – Jul 4

Peppers, eggplantStart indoors · Apr 4 – Apr 18

Peppers, eggplantTransplant · Jun 27 – Jul 11

BeansSow outdoors · Jun 20 – Jul 4

Sweet cornSow outdoors · Jun 20 – Jul 4

Cucumbers, squashSow outdoors · Jun 20 – Jul 4

Fall lettuce, spinachSow outdoors · Jul 11 – Jul 25

GarlicPlant cloves · Aug 22 – Sep 26

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 13) and first fall frost (Sep 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 59702 came on Apr 18 — 18 days earlier than the 1991–2020 average (May 6).

average
May 62026
Apr 18

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 4a in Montana

439 plants native to the lower 48 states, recorded in Montana, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. 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 Butte, MT.

Soil in Butte, MT

The soil mapped at the center of ZIP 59702 is Moosejaw — mucky peat, very poorly drained.

TextureMucky peattop layer

pH6.5neutral; most vegetables like 6.0–7.0

DrainageVery poorly drainedconsider raised beds

Organic matter70%high

Hydrologic groupA/Ddrains fast once dried out; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Moosejaw, occasionally flooded-Highrye-Silas, occasionally flooded complex, 2 to 12 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 59702; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Butte, MT

Summer high81 °Faverage high, July

Winter low7 °Faverage low, December

Hot days8days a year at 90 °F or more

Freezing nights220nights a year at 32 °F or less

Growing degree days1,210base 50 °F — the season’s usable heat

Longest day15 h 45 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)

Precipitation12.8 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Butte Bert Mooney Airport, MT (7 mi away); precipitation: Butte Bert Mooney Airport, MT (7 mi away). Daylight is calculated from latitude.

ZIP codes in Butte

Montana planting zones →

Questions about Butte

What planting zone is Butte, MT?

Butte, MT is in USDA hardiness zones 4a to 5a on the 2023 map (4a: −30 to −25 °F; 4b: −25 to −20 °F; 5a: −20 to −15 °F).

When is the last frost in Butte, MT?

The median last spring frost is June 13 and the median first fall frost is September 5 (NOAA 1991–2020 normals, Butte Bert Mooney Airport station).

When can I plant a garden in Butte, MT?

Cool-season crops like peas and spinach go in around May 2 – May 23; tomatoes, peppers, beans and squash after about Jun 20, once frost risk has passed.

What kind of onions grow in Butte, MT?

Long-day onions: the longest day is 15 h 45 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Butte, MT get?

About 12.8 inches of precipitation a year (NOAA 1991–2020 normals).