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

Planting zone for 59018 — Clyde Park, MT

ZIP code 59018 (Clyde Park, Park County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is June 4 and the first fall frost September 6.

Where ZIP 59018 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 frostJun 4
First frostSep 6
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 Clyde Park, 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 Clyde Park, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 4median — 50% chance of a later frost
Safe for tender plantsJune 23only 10% chance of frost after
First fall frostSeptember 6median — 10% chance by Aug 28
Growing season92 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 16 and returns around September 13.

From the NOAA station Wilsall 1s, MT — 10 miles away, elevation 5,017 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 59018

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 23 – May 7
SpinachSow outdoors · Apr 23 – May 14
Broccoli, cabbageStart indoors · Mar 26 – Apr 9
Broccoli, cabbageTransplant · May 14 – May 28
Onion setsPlant outdoors · May 7 – May 21
PotatoesPlant outdoors · May 14 – May 28
LettuceSow outdoors · May 7 – May 21
Carrots, beetsSow outdoors · May 14 – May 28
TomatoesStart indoors · Apr 9 – Apr 23
TomatoesTransplant · Jun 11 – Jun 25
Peppers, eggplantStart indoors · Mar 26 – Apr 9
Peppers, eggplantTransplant · Jun 18 – Jul 2
BeansSow outdoors · Jun 11 – Jun 25
Sweet cornSow outdoors · Jun 11 – Jun 25
Cucumbers, squashSow outdoors · Jun 11 – Jun 25
Fall lettuce, spinachSow outdoors · Jul 12 – Jul 26
GarlicPlant cloves · Aug 23 – Sep 27
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 4) and first fall frost (Sep 6) 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 59018 came on Mar 23 — 25 days earlier than the 1991–2020 average (Apr 17).

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 Clyde Park, MT.

Soil in Clyde Park, MT

The soil mapped at the center of ZIP 59018 is Cabba — silty clay loam, well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH7.8slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Cabba-Bacbuster-Gnojek complex, 2 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 59018; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Clyde Park, MT

Summer high84 °Faverage high, July
Winter low10 °Faverage low, December
Hot days9days a year at 90 °F or more
Freezing nights220nights a year at 32 °F or less
Growing degree days1,350base 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)
Precipitation14.9 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 31 °F, low 11 °F 31°11° JanFebruary: average high 36 °F, low 14 °F 36°14° FebMarch: average high 43 °F, low 21 °F 43°21° MarApril: average high 52 °F, low 26 °F 52°26° AprMay: average high 61 °F, low 37 °F 61°37° MayJune: average high 71 °F, low 41 °F 71°41° JunJuly: average high 84 °F, low 49 °F 84°49° JulAugust: average high 82 °F, low 47 °F 82°47° AugSeptember: average high 70 °F, low 35 °F 70°35° SepOctober: average high 56 °F, low 29 °F 56°29° OctNovember: average high 42 °F, low 15 °F 42°15° NovDecember: average high 34 °F, low 10 °F 34°10° Dec

Precipitation by month inches

0″1″2″3″January: 0.51 in precipitation 0.5 JanFebruary: 0.56 in precipitation 0.6 FebMarch: 1.07 in precipitation 1.1 MarApril: 1.75 in precipitation 1.8 AprMay: 2.27 in precipitation 2.3 MayJune: 2.35 in precipitation 2.4 JunJuly: 1.40 in precipitation 1.4 JulAugust: 1.13 in precipitation 1.1 AugSeptember: 1.32 in precipitation 1.3 SepOctober: 1.31 in precipitation 1.3 OctNovember: 0.74 in precipitation 0.7 NovDecember: 0.48 in precipitation 0.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Wilsall 1s, MT (10 mi away); precipitation: Wilsall 1s, MT (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

590864b
Wilsall, MT · 15 mi
590825a
Springdale, MT · 16 mi
597155a
Bozeman, MT · 17 mi
590475a
Livingston, MT · 19 mi
597195a
Bozeman, MT · 20 mi
597715a
Bozeman, MT · 26 mi
597725a
Bozeman, MT · 26 mi
597145a
Belgrade, MT · 26 mi

Montana planting zones →

Questions about 59018

What planting zone is ZIP code 59018?

ZIP code 59018 (Clyde Park, 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 Clyde Park, MT?

The median last spring frost (32 °F) near 59018 is June 4; after June 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wilsall 1s station.

When is the first frost in Clyde Park, MT?

The median first fall frost near 59018 is September 6, giving a median frost-free growing season of 92 days.

When should I plant tomatoes in 59018?

Start tomato seeds indoors around Apr 9 – Apr 23 and set transplants outside around Jun 11 – Jun 25, one to three weeks after the median last frost.

How much rain and snow does 59018 get?

About 14.9 inches of precipitation a year (NOAA 1991–2020 normals, Wilsall 1s station).

How hot do summers get in Clyde Park, MT?

The average high peaks at 84 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 59018 have?

The USDA soil survey maps Cabba at the center of ZIP 59018: silty clay loam, well drained, pH about 7.8 (slightly alkaline).

Did spring come early in Clyde Park, MT in 2026?

Spring leaf-out near 59018 came on Mar 23 in 2026, 25 days earlier than the 1991–2020 average (Apr 17), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Clyde Park, MT?

Long-day onions: the longest day near 59018 is 15 h 44 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59018 change?

Yes. The 2012 USDA map put 59018 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.