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

Planting zone for 57661 — Whitehorse, SD

ZIP code 57661 (Whitehorse, Dewey County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 10 and the first fall frost September 30.

Where ZIP 57661 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 10
First frostSep 30
2012 zone4b

Same zone as on the 2012 map. 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 Whitehorse, SD…

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 Whitehorse, SD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 10median — 50% chance of a later frost
Safe for tender plantsMay 23only 10% chance of frost after
First fall frostSeptember 30median — 10% chance by Sep 17
Growing season141 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 7.

From the NOAA station Timber Lake, SD — 12 miles away, elevation 2,172 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 57661

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 29 – Apr 12
SpinachSow outdoors · Mar 29 – Apr 19
Broccoli, cabbageStart indoors · Mar 1 – Mar 15
Broccoli, cabbageTransplant · Apr 19 – May 3
Onion setsPlant outdoors · Apr 12 – Apr 26
PotatoesPlant outdoors · Apr 19 – May 3
LettuceSow outdoors · Apr 12 – Apr 26
Carrots, beetsSow outdoors · Apr 19 – May 3
TomatoesStart indoors · Mar 15 – Mar 29
TomatoesTransplant · May 17 – May 31
Peppers, eggplantStart indoors · Mar 1 – Mar 15
Peppers, eggplantTransplant · May 24 – Jun 7
BeansSow outdoors · May 17 – May 31
Sweet cornSow outdoors · May 17 – May 31
Cucumbers, squashSow outdoors · May 17 – May 31
Fall lettuce, spinachSow outdoors · Aug 5 – Aug 19
GarlicPlant cloves · Sep 16 – Oct 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 10) and first fall frost (Sep 30) 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 57661 came on Mar 28 — 17 days earlier than the 1991–2020 average (Apr 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).

Native plants for zone 4b in South Dakota

430 plants native to the lower 48 states, recorded in South Dakota, 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 basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican 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 °Fblack maple100 ft · blooms late spring · low shade tolerance · to −47 °Fblack walnut100 ft · blooms late spring · high shade tolerance · to −28 °F

Shrubs 65

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °Falderleaf mountain mahogany15 ft · blooms late spring · medium shade tolerance · to −41 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fbeaked hazelnut15 ft · blooms early spring · low shade tolerance · to −47 °F

Wildflowers & perennials 191

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 eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °F

Grasses 138

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 timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °F

Vines 5

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °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 Whitehorse, SD.

Soil in Whitehorse, SD

The soil mapped at the center of ZIP 57661 is Sansarc — clay, well drained.

TextureClayholds water and nutrients; slow to drain and warm up
pH7.6slightly alkaline; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.6%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Sansarc-Opal clays, 9 to 25 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 57661; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Whitehorse, SD

Summer high86 °Faverage high, July
Winter low7 °Faverage low, January
Hot days24days a year at 90 °F or more
Freezing nights173nights a year at 32 °F or less
Growing degree days2,619base 50 °F — the season’s usable heat
Longest day15 h 39 mindaylight on June 21
Shortest day8 h 44 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation19.4 inper year, rain and melted snow
Snowfall41 inper year; 79 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 27 °F, low 7 °F 27°7° JanFebruary: average high 31 °F, low 11 °F 31°11° FebMarch: average high 44 °F, low 21 °F 44°21° MarApril: average high 58 °F, low 32 °F 58°32° AprMay: average high 69 °F, low 43 °F 69°43° MayJune: average high 79 °F, low 54 °F 79°54° JunJuly: average high 86 °F, low 59 °F 86°59° JulAugust: average high 85 °F, low 58 °F 85°58° AugSeptember: average high 76 °F, low 48 °F 76°48° SepOctober: average high 59 °F, low 35 °F 59°35° OctNovember: average high 43 °F, low 22 °F 43°22° NovDecember: average high 30 °F, low 11 °F 30°11° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.49 in precipitation, 6.4 in snowfall 0.5❄6 JanFebruary: 0.67 in precipitation, 7.5 in snowfall 0.7❄8 FebMarch: 1.00 in precipitation, 6.5 in snowfall 1.0❄7 MarApril: 1.83 in precipitation, 5.2 in snowfall 1.8❄5 AprMay: 2.90 in precipitation, 0.6 in snowfall 2.9❄1 MayJune: 3.56 in precipitation 3.6 JunJuly: 2.85 in precipitation 2.9 JulAugust: 1.78 in precipitation 1.8 AugSeptember: 1.53 in precipitation 1.5 SepOctober: 1.66 in precipitation, 2.3 in snowfall 1.7❄2 OctNovember: 0.57 in precipitation, 4.4 in snowfall 0.6❄4 NovDecember: 0.57 in precipitation, 8.3 in snowfall 0.6❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Timber Lake, SD (12 mi away); precipitation: Timber Lake, SD (12 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.

576304b
Glencross, SD · 8 mi
576564b
Timber Lake, SD · 12 mi
576524b
Ridgeview, SD · 17 mi
576574b
Trail City, SD · 20 mi
576254b
Eagle Butte, SD · 20 mi
576364b
Lantry, SD · 28 mi
576394a
Little Eagle, SD · 30 mi
576014b
Mobridge, SD · 30 mi

South Dakota planting zones →

Questions about 57661

What planting zone is ZIP code 57661?

ZIP code 57661 (Whitehorse, SD) 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 Whitehorse, SD?

The median last spring frost (32 °F) near 57661 is May 10; after May 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Timber Lake station.

When is the first frost in Whitehorse, SD?

The median first fall frost near 57661 is September 30, giving a median frost-free growing season of 141 days.

When should I plant tomatoes in 57661?

Start tomato seeds indoors around Mar 15 – Mar 29 and set transplants outside around May 17 – May 31, one to three weeks after the median last frost.

How much rain and snow does 57661 get?

About 19.4 inches of precipitation a year and 41 inches of snowfall (NOAA 1991–2020 normals, Timber Lake station).

How hot do summers get in Whitehorse, SD?

The average high peaks at 86 °F in July, with about 24 days a year at 90 °F or more.

What kind of soil does 57661 have?

The USDA soil survey maps Sansarc at the center of ZIP 57661: clay, well drained, pH about 7.6 (slightly alkaline).

Did spring come early in Whitehorse, SD in 2026?

Spring leaf-out near 57661 came on Mar 28 in 2026, 17 days earlier than the 1991–2020 average (Apr 14), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Whitehorse, SD?

Long-day onions: the longest day near 57661 is 15 h 39 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).