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

Planting zone for 57233 — Erwin, SD

ZIP code 57233 (Erwin, Kingsbury County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 5 and the first fall frost October 4.

Where ZIP 57233 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 5
First frostOct 4
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 Erwin, 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 Erwin, SD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 5median — 50% chance of a later frost
Safe for tender plantsMay 20only 10% chance of frost after
First fall frostOctober 4median — 10% chance by Sep 23
Growing season151 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 28 and returns around October 14.

From the NOAA station De Smet, SD — 12 miles away, elevation 1,706 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 57233

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 24 – Apr 7
SpinachSow outdoors · Mar 24 – Apr 14
Broccoli, cabbageStart indoors · Feb 24 – Mar 10
Broccoli, cabbageTransplant · Apr 14 – Apr 28
Onion setsPlant outdoors · Apr 7 – Apr 21
PotatoesPlant outdoors · Apr 14 – Apr 28
LettuceSow outdoors · Apr 7 – Apr 21
Carrots, beetsSow outdoors · Apr 14 – Apr 28
TomatoesStart indoors · Mar 10 – Mar 24
TomatoesTransplant · May 12 – May 26
Peppers, eggplantStart indoors · Feb 24 – Mar 10
Peppers, eggplantTransplant · May 19 – Jun 2
BeansSow outdoors · May 12 – May 26
Sweet cornSow outdoors · May 12 – May 26
Cucumbers, squashSow outdoors · May 12 – May 26
Fall lettuce, spinachSow outdoors · Aug 9 – Aug 23
GarlicPlant cloves · Sep 20 – Oct 25
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 5) and first fall frost (Oct 4) 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 57233 came on Apr 11 — 6 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 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 Erwin, SD.

Soil in Erwin, SD

The soil mapped at the center of ZIP 57233 is Parnell — silty clay loam, very poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH7.0neutral; most vegetables like 6.0–7.0
DrainageVery poorly drainedconsider raised beds
Organic matter8%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classNot prime farmlandUSDA classification

Map unit: Parnell silty clay loam.

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 57233; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Erwin, SD

Summer high82 °Faverage high, July
Winter low5 °Faverage low, January
Hot days10days a year at 90 °F or more
Freezing nights165nights a year at 32 °F or less
Growing degree days2,461base 50 °F — the season’s usable heat
Longest day15 h 33 mindaylight on June 21
Shortest day8 h 49 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation26.5 inper year, rain and melted snow
Snowfall48 inper year; 78 days with snow on the ground

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 23 °F, low 5 °F 23°5° JanFebruary: average high 29 °F, low 9 °F 29°9° FebMarch: average high 41 °F, low 21 °F 41°21° MarApril: average high 55 °F, low 33 °F 55°33° AprMay: average high 67 °F, low 45 °F 67°45° MayJune: average high 77 °F, low 56 °F 77°56° JunJuly: average high 82 °F, low 61 °F 82°61° JulAugust: average high 79 °F, low 59 °F 79°59° AugSeptember: average high 72 °F, low 50 °F 72°50° SepOctober: average high 57 °F, low 36 °F 57°36° OctNovember: average high 41 °F, low 22 °F 41°22° NovDecember: average high 28 °F, low 10 °F 28°10° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 0.68 in precipitation, 8.1 in snowfall 0.7❄8 JanFebruary: 0.67 in precipitation, 8 in snowfall 0.7❄8 FebMarch: 1.21 in precipitation, 6.4 in snowfall 1.2❄6 MarApril: 2.40 in precipitation, 6.9 in snowfall 2.4❄7 AprMay: 3.32 in precipitation 3.3 MayJune: 4.42 in precipitation 4.4 JunJuly: 3.46 in precipitation 3.5 JulAugust: 3.28 in precipitation 3.3 AugSeptember: 3.00 in precipitation 3.0 SepOctober: 2.35 in precipitation, 1.3 in snowfall 2.4❄1 OctNovember: 0.91 in precipitation, 7.3 in snowfall 0.9❄7 NovDecember: 0.79 in precipitation, 9.7 in snowfall 0.8❄10 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: De Smet, SD (12 mi away); precipitation: Bryant, SD (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4b.

572214b
Bryant, SD · 7 mi
572494b
Lake Preston, SD · 9 mi
572144b
Badger, SD · 10 mi
572484b
Lake Norden, SD · 12 mi
572314b
De Smet, SD · 13 mi
572414b
Hayti, SD · 16 mi
572124b
Arlington, SD · 16 mi
572784b
Willow Lake, SD · 17 mi

South Dakota planting zones →

Questions about 57233

What planting zone is ZIP code 57233?

ZIP code 57233 (Erwin, 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 Erwin, SD?

The median last spring frost (32 °F) near 57233 is May 5; after May 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, De Smet station.

When is the first frost in Erwin, SD?

The median first fall frost near 57233 is October 4, giving a median frost-free growing season of 151 days.

When should I plant tomatoes in 57233?

Start tomato seeds indoors around Mar 10 – Mar 24 and set transplants outside around May 12 – May 26, one to three weeks after the median last frost.

How much rain and snow does 57233 get?

About 26.5 inches of precipitation a year and 48 inches of snowfall (NOAA 1991–2020 normals, Bryant station).

How hot do summers get in Erwin, SD?

The average high peaks at 82 °F in July, with about 10 days a year at 90 °F or more.

What kind of soil does 57233 have?

The USDA soil survey maps Parnell at the center of ZIP 57233: silty clay loam, very poorly drained, pH about 7.0 (neutral).

Did spring come early in Erwin, SD in 2026?

Spring leaf-out near 57233 came on Apr 11 in 2026, 6 days earlier than the 1991–2020 average (Apr 17), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Erwin, SD?

Long-day onions: the longest day near 57233 is 15 h 33 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).