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

Planting zone for 57639 — Little Eagle, SD

ZIP code 57639 (Little Eagle, Corson County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 12 and the first fall frost September 28.

Where ZIP 57639 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 12
First frostSep 28
2012 zone4a

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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Little Eagle, 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 Little Eagle, SD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 12median — 50% chance of a later frost
Safe for tender plantsMay 25only 10% chance of frost after
First fall frostSeptember 28median — 10% chance by Sep 16
Growing season137 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 3 and returns around October 5.

From the NOAA station Mc Laughlin, SD — 9 miles away, elevation 2,001 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 57639

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 31 – Apr 14
SpinachSow outdoors · Mar 31 – Apr 21
Broccoli, cabbageStart indoors · Mar 3 – Mar 17
Broccoli, cabbageTransplant · Apr 21 – May 5
Onion setsPlant outdoors · Apr 14 – Apr 28
PotatoesPlant outdoors · Apr 21 – May 5
LettuceSow outdoors · Apr 14 – Apr 28
Carrots, beetsSow outdoors · Apr 21 – May 5
TomatoesStart indoors · Mar 17 – Mar 31
TomatoesTransplant · May 19 – Jun 2
Peppers, eggplantStart indoors · Mar 3 – Mar 17
Peppers, eggplantTransplant · May 26 – Jun 9
BeansSow outdoors · May 19 – Jun 2
Sweet cornSow outdoors · May 19 – Jun 2
Cucumbers, squashSow outdoors · May 19 – Jun 2
Fall lettuce, spinachSow outdoors · Aug 3 – Aug 17
GarlicPlant cloves · Sep 14 – Oct 19
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 12) and first fall frost (Sep 28) 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 57639 came on Apr 7 — 9 days earlier than the 1991–2020 average (Apr 16).

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 Little Eagle, SD

The soil mapped at the center of ZIP 57639 is Opal — clay, well drained.

TextureClayholds water and nutrients; slow to drain and warm up
pH7.2neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Opal-Dupree clays, 2 to 9 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 57639; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Little Eagle, SD

Summer high85 °Faverage high, July
Winter low4 °Faverage low, January
Hot days24days a year at 90 °F or more
Freezing nights186nights a year at 32 °F or less
Growing degree days2,370base 50 °F — the season’s usable heat
Longest day15 h 43 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)
Precipitation20.1 inper year, rain and melted snow
Snowfall35 inper year

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 4 °F 24°4° JanFebruary: average high 28 °F, low 7 °F 28°7° FebMarch: average high 42 °F, low 19 °F 42°19° MarApril: average high 56 °F, low 30 °F 56°30° AprMay: average high 68 °F, low 42 °F 68°42° MayJune: average high 78 °F, low 53 °F 78°53° JunJuly: average high 85 °F, low 58 °F 85°58° JulAugust: average high 84 °F, low 55 °F 84°55° AugSeptember: average high 74 °F, low 45 °F 74°45° SepOctober: average high 57 °F, low 32 °F 57°32° OctNovember: average high 41 °F, low 19 °F 41°19° NovDecember: average high 29 °F, low 9 °F 29°9° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.50 in precipitation, 7.5 in snowfall 0.5❄8 JanFebruary: 0.49 in precipitation, 6.5 in snowfall 0.5❄7 FebMarch: 0.94 in precipitation, 3.7 in snowfall 0.9❄4 MarApril: 1.69 in precipitation, 2.1 in snowfall 1.7❄2 AprMay: 3.17 in precipitation, 0.2 in snowfall 3.2 MayJune: 3.34 in precipitation 3.3 JunJuly: 3.03 in precipitation 3.0 JulAugust: 2.47 in precipitation 2.5 AugSeptember: 1.45 in precipitation 1.4 SepOctober: 1.77 in precipitation, 0.7 in snowfall 1.8❄1 OctNovember: 0.65 in precipitation, 4 in snowfall 0.7❄4 NovDecember: 0.58 in precipitation, 10.2 in snowfall 0.6❄10 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mc Laughlin, SD (9 mi away); precipitation: Mc Laughlin, SD (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

576424b
Mc Laughlin, SD · 9 mi
576574b
Trail City, SD · 11 mi
576584b
Wakpala, SD · 12 mi
576214b
Bullhead, SD · 15 mi
576594b
Walker, SD · 20 mi
576564b
Timber Lake, SD · 23 mi
576304b
Glencross, SD · 24 mi
576314b
Glenham, SD · 25 mi

South Dakota planting zones →

Questions about 57639

What planting zone is ZIP code 57639?

ZIP code 57639 (Little Eagle, SD) 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 Little Eagle, SD?

The median last spring frost (32 °F) near 57639 is May 12; after May 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mc Laughlin station.

When is the first frost in Little Eagle, SD?

The median first fall frost near 57639 is September 28, giving a median frost-free growing season of 137 days.

When should I plant tomatoes in 57639?

Start tomato seeds indoors around Mar 17 – Mar 31 and set transplants outside around May 19 – Jun 2, one to three weeks after the median last frost.

How much rain and snow does 57639 get?

About 20.1 inches of precipitation a year and 35 inches of snowfall (NOAA 1991–2020 normals, Mc Laughlin station).

How hot do summers get in Little Eagle, SD?

The average high peaks at 85 °F in July, with about 24 days a year at 90 °F or more.

What kind of soil does 57639 have?

The USDA soil survey maps Opal at the center of ZIP 57639: clay, well drained, pH about 7.2 (neutral).

Did spring come early in Little Eagle, SD in 2026?

Spring leaf-out near 57639 came on Apr 7 in 2026, 9 days earlier than the 1991–2020 average (Apr 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Little Eagle, SD?

Long-day onions: the longest day near 57639 is 15 h 43 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).