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

Planting zone for 59212 — Bainville, MT

ZIP code 59212 (Bainville, Roosevelt County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 21 and the first fall frost September 20.

Where ZIP 59212 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.

Zone4a−30 to −25 °F
Coldest night−34.4 to −31.7 °C
Last frostMay 21
First frostSep 20
2012 zone3b

Was 3b 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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Bainville, 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 Bainville, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 21median — 50% chance of a later frost
Safe for tender plantsJune 3only 10% chance of frost after
First fall frostSeptember 20median — 10% chance by Sep 6
Growing season120 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 10 and returns around September 27.

From the NOAA station Culbertson, MT — 17 miles away, elevation 1,939 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 59212

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 9 – Apr 23
SpinachSow outdoors · Apr 9 – Apr 30
Broccoli, cabbageStart indoors · Mar 12 – Mar 26
Broccoli, cabbageTransplant · Apr 30 – May 14
Onion setsPlant outdoors · Apr 23 – May 7
PotatoesPlant outdoors · Apr 30 – May 14
LettuceSow outdoors · Apr 23 – May 7
Carrots, beetsSow outdoors · Apr 30 – May 14
TomatoesStart indoors · Mar 26 – Apr 9
TomatoesTransplant · May 28 – Jun 11
Peppers, eggplantStart indoors · Mar 12 – Mar 26
Peppers, eggplantTransplant · Jun 4 – Jun 18
BeansSow outdoors · May 28 – Jun 11
Sweet cornSow outdoors · May 28 – Jun 11
Cucumbers, squashSow outdoors · May 28 – Jun 11
Fall lettuce, spinachSow outdoors · Jul 26 – Aug 9
GarlicPlant cloves · Sep 6 – Oct 11
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 21) and first fall frost (Sep 20) 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 59212 came on Apr 20 — about the same time as the 1991–2020 average (Apr 19).

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).

Soil in Bainville, MT

The soil mapped at the center of ZIP 59212 is Zahill — loam, well drained.

TextureLoama good balance for most vegetables
pH7.9alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Zahill-Vida loams, 4 to 15 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 59212; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Bainville, MT

Summer high87 °Faverage high, July
Winter low2 °Faverage low, January
Hot days31days a year at 90 °F or more
Freezing nights191nights a year at 32 °F or less
Growing degree days2,350base 50 °F — the season’s usable heat
Longest day16 h 05 mindaylight on June 21
Shortest day8 h 20 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation14.5 inper year, rain and melted snow

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 24 °F, low 2 °F 24°2° JanFebruary: average high 30 °F, low 7 °F 30°7° FebMarch: average high 44 °F, low 18 °F 44°18° MarApril: average high 59 °F, low 30 °F 59°30° AprMay: average high 71 °F, low 40 °F 71°40° MayJune: average high 79 °F, low 50 °F 79°50° JunJuly: average high 87 °F, low 56 °F 87°56° JulAugust: average high 87 °F, low 54 °F 87°54° AugSeptember: average high 76 °F, low 44 °F 76°44° SepOctober: average high 59 °F, low 31 °F 59°31° OctNovember: average high 41 °F, low 18 °F 41°18° NovDecember: average high 28 °F, low 7 °F 28°7° Dec

Precipitation by month inches

0″1″2″3″January: 0.36 in precipitation 0.4 JanFebruary: 0.31 in precipitation 0.3 FebMarch: 0.49 in precipitation 0.5 MarApril: 0.94 in precipitation 0.9 AprMay: 2.25 in precipitation 2.3 MayJune: 2.88 in precipitation 2.9 JunJuly: 2.73 in precipitation 2.7 JulAugust: 1.40 in precipitation 1.4 AugSeptember: 1.33 in precipitation 1.3 SepOctober: 0.91 in precipitation 0.9 OctNovember: 0.49 in precipitation 0.5 NovDecember: 0.43 in precipitation 0.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Culbertson, MT (17 mi away); precipitation: Culbertson, MT (17 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

588014a
Williston, ND · 17 mi
592184a
Culbertson, MT · 19 mi
592423b
Homestead, MT · 19 mi
592264a
Froid, MT · 20 mi
588534a
Trenton, ND · 22 mi
592214a
Fairview, MT · 22 mi
592193b
Dagmar, MT · 24 mi
588024a
Williston, ND · 25 mi

Montana planting zones →

Questions about 59212

What planting zone is ZIP code 59212?

ZIP code 59212 (Bainville, MT) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Bainville, MT?

The median last spring frost (32 °F) near 59212 is May 21; after June 3 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Culbertson station.

When is the first frost in Bainville, MT?

The median first fall frost near 59212 is September 20, giving a median frost-free growing season of 120 days.

When should I plant tomatoes in 59212?

Start tomato seeds indoors around Mar 26 – Apr 9 and set transplants outside around May 28 – Jun 11, one to three weeks after the median last frost.

How much rain and snow does 59212 get?

About 14.5 inches of precipitation a year (NOAA 1991–2020 normals, Culbertson station).

How hot do summers get in Bainville, MT?

The average high peaks at 87 °F in July, with about 31 days a year at 90 °F or more.

What kind of soil does 59212 have?

The USDA soil survey maps Zahill at the center of ZIP 59212: loam, well drained, pH about 7.9 (alkaline).

Did spring come early in Bainville, MT in 2026?

Spring leaf-out near 59212 came on Apr 20 in 2026, about the same as the 1991–2020 average (Apr 19), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Bainville, MT?

Long-day onions: the longest day near 59212 is 16 h 05 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59212 change?

Yes. The 2012 USDA map put 59212 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.