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

Planting zone for 59471 — Roy, MT

ZIP code 59471 (Roy, Fergus County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 14 and the first fall frost September 24.

Where ZIP 59471 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.

Zone4b−25 to −20 °F
Coldest night−31.7 to −28.9 °C
Last frostMay 14
First frostSep 24
2012 zone4a

Was 4a 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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Roy, 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 Roy, MT

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 14median — 50% chance of a later frost
Safe for tender plantsMay 29only 10% chance of frost after
First fall frostSeptember 24median — 10% chance by Sep 12
Growing season134 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 2 and returns around October 2.

From the NOAA station Roy 8 Ne, MT — 5 miles away, elevation 3,084 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 59471

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 2 – Apr 16
SpinachSow outdoors · Apr 2 – Apr 23
Broccoli, cabbageStart indoors · Mar 5 – Mar 19
Broccoli, cabbageTransplant · Apr 23 – May 7
Onion setsPlant outdoors · Apr 16 – Apr 30
PotatoesPlant outdoors · Apr 23 – May 7
LettuceSow outdoors · Apr 16 – Apr 30
Carrots, beetsSow outdoors · Apr 23 – May 7
TomatoesStart indoors · Mar 19 – Apr 2
TomatoesTransplant · May 21 – Jun 4
Peppers, eggplantStart indoors · Mar 5 – Mar 19
Peppers, eggplantTransplant · May 28 – Jun 11
BeansSow outdoors · May 21 – Jun 4
Sweet cornSow outdoors · May 21 – Jun 4
Cucumbers, squashSow outdoors · May 21 – Jun 4
Fall lettuce, spinachSow outdoors · Jul 30 – Aug 13
GarlicPlant cloves · Sep 10 – Oct 15
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 14) and first fall frost (Sep 24) 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 59471 came on Mar 23 — 16 days earlier than the 1991–2020 average (Apr 8).

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 4b in Montana

506 plants native to the lower 48 states, recorded in Montana, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. Each links to its USDA PLANTS profile.

Trees 23

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 87

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 229

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 155

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 Roy, MT.

Soil in Roy, MT

The soil mapped at the center of ZIP 59471 is Thebo — clay, well drained.

TextureClayholds water and nutrients; slow to drain and warm up
pH7.5slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.25%low — add compost
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Thebo-Weingart-Absher clays, 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 59471; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Roy, MT

Summer high86 °Faverage high, July
Winter low10 °Faverage low, January
Hot days26days a year at 90 °F or more
Freezing nights177nights a year at 32 °F or less
Growing degree days2,182base 50 °F — the season’s usable heat
Longest day15 h 58 mindaylight on June 21
Shortest day8 h 27 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation13.3 inper year, rain and melted snow
Snowfall36 inper year; 53 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 34 °F, low 10 °F 34°10° JanFebruary: average high 37 °F, low 13 °F 37°13° FebMarch: average high 48 °F, low 22 °F 48°22° MarApril: average high 58 °F, low 30 °F 58°30° AprMay: average high 68 °F, low 40 °F 68°40° MayJune: average high 76 °F, low 48 °F 76°48° JunJuly: average high 86 °F, low 54 °F 86°54° JulAugust: average high 86 °F, low 53 °F 86°53° AugSeptember: average high 76 °F, low 43 °F 76°43° SepOctober: average high 60 °F, low 32 °F 60°32° OctNovember: average high 46 °F, low 21 °F 46°21° NovDecember: average high 36 °F, low 12 °F 36°12° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.45 in precipitation, 7.7 in snowfall 0.5❄8 JanFebruary: 0.39 in precipitation, 4.7 in snowfall 0.4❄5 FebMarch: 0.52 in precipitation, 6.8 in snowfall 0.5❄7 MarApril: 1.29 in precipitation, 2.6 in snowfall 1.3❄3 AprMay: 2.51 in precipitation, 0.6 in snowfall 2.5❄1 MayJune: 2.63 in precipitation 2.6 JunJuly: 1.74 in precipitation 1.7 JulAugust: 1.29 in precipitation 1.3 AugSeptember: 0.94 in precipitation 0.9 SepOctober: 0.67 in precipitation, 1.9 in snowfall 0.7❄2 OctNovember: 0.47 in precipitation, 5.5 in snowfall 0.5❄6 NovDecember: 0.42 in precipitation, 6.5 in snowfall 0.4❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Roy 8 Ne, MT (5 mi away); precipitation: Roy 8 Ne, MT (5 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4b.

594894b
Winifred, MT · 25 mi
590324b
Grass Range, MT · 28 mi
590844b
Teigen, MT · 28 mi
594514b
Hilger, MT · 29 mi
594574b
Lewistown, MT · 32 mi
590874b
Winnett, MT · 32 mi
595464b
Zortman, MT · 34 mi
595354b
Lloyd, MT · 42 mi

Montana planting zones →

Questions about 59471

What planting zone is ZIP code 59471?

ZIP code 59471 (Roy, MT) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Roy, MT?

The median last spring frost (32 °F) near 59471 is May 14; after May 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Roy 8 Ne station.

When is the first frost in Roy, MT?

The median first fall frost near 59471 is September 24, giving a median frost-free growing season of 134 days.

When should I plant tomatoes in 59471?

Start tomato seeds indoors around Mar 19 – Apr 2 and set transplants outside around May 21 – Jun 4, one to three weeks after the median last frost.

How much rain and snow does 59471 get?

About 13.3 inches of precipitation a year and 36 inches of snowfall (NOAA 1991–2020 normals, Roy 8 Ne station).

How hot do summers get in Roy, MT?

The average high peaks at 86 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 59471 have?

The USDA soil survey maps Thebo at the center of ZIP 59471: clay, well drained, pH about 7.5 (slightly alkaline).

Did spring come early in Roy, MT in 2026?

Spring leaf-out near 59471 came on Mar 23 in 2026, 16 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Roy, MT?

Long-day onions: the longest day near 59471 is 15 h 58 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 59471 change?

Yes. The 2012 USDA map put 59471 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.