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

Planting zone for 59019 — Columbus, MT

ZIP code 59019 (Columbus, Stillwater County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 27 and the first fall frost September 14.

Where ZIP 59019 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 27

First frostSep 14

2012 zone4b

Was 4b 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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Columbus, 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 Columbus, MT

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 27median — 50% chance of a later frost

Safe for tender plantsJune 12only 10% chance of frost after

First fall frostSeptember 14median — 10% chance by Sep 1

Growing season108 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 13 and returns around September 26.

From the NOAA station Columbus, MT — 2 miles away, elevation 3,603 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 59019

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 15 – Apr 29

SpinachSow outdoors · Apr 15 – May 6

Broccoli, cabbageStart indoors · Mar 18 – Apr 1

Broccoli, cabbageTransplant · May 6 – May 20

Onion setsPlant outdoors · Apr 29 – May 13

PotatoesPlant outdoors · May 6 – May 20

LettuceSow outdoors · Apr 29 – May 13

Carrots, beetsSow outdoors · May 6 – May 20

TomatoesStart indoors · Apr 1 – Apr 15

TomatoesTransplant · Jun 3 – Jun 17

Peppers, eggplantStart indoors · Mar 18 – Apr 1

Peppers, eggplantTransplant · Jun 10 – Jun 24

BeansSow outdoors · Jun 3 – Jun 17

Sweet cornSow outdoors · Jun 3 – Jun 17

Cucumbers, squashSow outdoors · Jun 3 – Jun 17

Fall lettuce, spinachSow outdoors · Jul 20 – Aug 3

GarlicPlant cloves · Aug 31 – Oct 5

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 27) and first fall frost (Sep 14) 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 59019 came on Mar 14 — 22 days earlier than the 1991–2020 average (Apr 5).

average
Apr 52026
Mar 14

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 Columbus, MT

The soil mapped at the center of ZIP 59019 is Attewan — loam, well drained.

TextureLoama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupBwater soaks in moderately

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Attewan loam, 0 to 4 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 59019; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Columbus, MT

Summer high85 °Faverage high, July

Winter low10 °Faverage low, January

Hot days28days a year at 90 °F or more

Freezing nights183nights a year at 32 °F or less

Growing degree days1,788base 50 °F — the season’s usable heat

Longest day15 h 42 mindaylight on June 21

Shortest day8 h 41 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation15.5 inper year, rain and melted snow

Snowfall48 inper year; 64 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Columbus, MT (2 mi away); precipitation: Columbus, MT (2 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.

590635a

Park City, MT · 13 mi

Absarokee, MT · 16 mi

590695a

Reed Point, MT · 18 mi

Montana planting zones →

Questions about 59019

What planting zone is ZIP code 59019?

ZIP code 59019 (Columbus, 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 Columbus, MT?

The median last spring frost (32 °F) near 59019 is May 27; after June 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Columbus station.

When is the first frost in Columbus, MT?

The median first fall frost near 59019 is September 14, giving a median frost-free growing season of 108 days.

When should I plant tomatoes in 59019?

Start tomato seeds indoors around Apr 1 – Apr 15 and set transplants outside around Jun 3 – Jun 17, one to three weeks after the median last frost.

How much rain and snow does 59019 get?

About 15.5 inches of precipitation a year and 48 inches of snowfall (NOAA 1991–2020 normals, Columbus station).

How hot do summers get in Columbus, MT?

The average high peaks at 85 °F in July, with about 28 days a year at 90 °F or more.

What kind of soil does 59019 have?

The USDA soil survey maps Attewan at the center of ZIP 59019: loam, well drained, pH about 7.0 (neutral).

Did spring come early in Columbus, MT in 2026?

Spring leaf-out near 59019 came on Mar 14 in 2026, 22 days earlier than the 1991–2020 average (Apr 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Columbus, MT?

Long-day onions: the longest day near 59019 is 15 h 42 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59019 change?

Yes. The 2012 USDA map put 59019 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.