Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 57536 — Harrold, SD

ZIP code 57536 (Harrold, Hughes County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 17 and the first fall frost September 24.

Where ZIP 57536 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 17

First frostSep 24

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 Harrold, 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 Harrold, SD

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 17median — 50% chance of a later frost

Safe for tender plantsMay 31only 10% chance of frost after

First fall frostSeptember 24median — 10% chance by Sep 10

Growing season129 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around October 2.

From the NOAA station Harrold 12 Ssw, SD — 4 miles away, elevation 1,703 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 57536

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 5 – Apr 19

SpinachSow outdoors · Apr 5 – Apr 26

Broccoli, cabbageStart indoors · Mar 8 – Mar 22

Broccoli, cabbageTransplant · Apr 26 – May 10

Onion setsPlant outdoors · Apr 19 – May 3

PotatoesPlant outdoors · Apr 26 – May 10

LettuceSow outdoors · Apr 19 – May 3

Carrots, beetsSow outdoors · Apr 26 – May 10

TomatoesStart indoors · Mar 22 – Apr 5

TomatoesTransplant · May 24 – Jun 7

Peppers, eggplantStart indoors · Mar 8 – Mar 22

Peppers, eggplantTransplant · May 31 – Jun 14

BeansSow outdoors · May 24 – Jun 7

Sweet cornSow outdoors · May 24 – Jun 7

Cucumbers, squashSow outdoors · May 24 – Jun 7

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 17) 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 57536 came on Mar 24 — 19 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
Mar 24

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.

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 Harrold, SD.

Soil in Harrold, SD

The soil mapped at the center of ZIP 57536 is Mobridge — silt loam, moderately well drained.

TextureSilt loama good balance for most vegetables

pH6.3slightly acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter5%high

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Mobridge silt loam, 0 to 2 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 57536; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Harrold, SD

Summer high87 °Faverage high, July

Winter low3 °Faverage low, January

Hot days32days a year at 90 °F or more

Freezing nights189nights a year at 32 °F or less

Growing degree days2,533base 50 °F — the season’s usable heat

Longest day15 h 32 mindaylight on June 21

Shortest day8 h 50 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation18.6 inper year, rain and melted snow

Snowfall40 inper year

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

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

Nearby ZIP codes

All 8 nearest ZIP codes share zone 4b.

Lower Brule, SD · 20 mi

Fort Thompson, SD · 25 mi

575014b

Pierre, SD · 27 mi

South Dakota planting zones →

Questions about 57536

What planting zone is ZIP code 57536?

ZIP code 57536 (Harrold, 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 Harrold, SD?

The median last spring frost (32 °F) near 57536 is May 17; after May 31 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Harrold 12 Ssw station.

When is the first frost in Harrold, SD?

The median first fall frost near 57536 is September 24, giving a median frost-free growing season of 129 days.

When should I plant tomatoes in 57536?

Start tomato seeds indoors around Mar 22 – Apr 5 and set transplants outside around May 24 – Jun 7, one to three weeks after the median last frost.

How much rain and snow does 57536 get?

About 18.6 inches of precipitation a year and 40 inches of snowfall (NOAA 1991–2020 normals, Harrold 12 Ssw station).

How hot do summers get in Harrold, SD?

The average high peaks at 87 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 57536 have?

The USDA soil survey maps Mobridge at the center of ZIP 57536: silt loam, moderately well drained, pH about 6.3 (slightly acidic).

Did spring come early in Harrold, SD in 2026?

Spring leaf-out near 57536 came on Mar 24 in 2026, 19 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Harrold, SD?

Long-day onions: the longest day near 57536 is 15 h 32 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).