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

Planting zone for 57239 — Grenville, SD

ZIP code 57239 (Grenville, Day County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 1 and the first fall frost October 12.

Where ZIP 57239 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 1

First frostOct 12

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 Grenville, 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 Grenville, SD

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 1median — 50% chance of a later frost

Safe for tender plantsMay 12only 10% chance of frost after

First fall frostOctober 12median — 10% chance by Sep 30

Growing season164 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 21 and returns around October 21.

From the NOAA station Waubay Natl Wild Life, SD — 6 miles away, elevation 1,828 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 57239

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 20 – Apr 3

SpinachSow outdoors · Mar 20 – Apr 10

Broccoli, cabbageStart indoors · Feb 20 – Mar 6

Broccoli, cabbageTransplant · Apr 10 – Apr 24

Onion setsPlant outdoors · Apr 3 – Apr 17

PotatoesPlant outdoors · Apr 10 – Apr 24

LettuceSow outdoors · Apr 3 – Apr 17

Carrots, beetsSow outdoors · Apr 10 – Apr 24

TomatoesStart indoors · Mar 6 – Mar 20

TomatoesTransplant · May 8 – May 22

Peppers, eggplantStart indoors · Feb 20 – Mar 6

Peppers, eggplantTransplant · May 15 – May 29

BeansSow outdoors · May 8 – May 22

Sweet cornSow outdoors · May 8 – May 22

Cucumbers, squashSow outdoors · May 8 – May 22

Fall lettuce, spinachSow outdoors · Aug 17 – Aug 31

GarlicPlant cloves · Sep 28 – Nov 2

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 1) and first fall frost (Oct 12) 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 57239 came on Apr 18 — about the same time as the 1991–2020 average (Apr 20).

average
Apr 202026
Apr 18

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 Grenville, SD.

Soil in Grenville, SD

The soil mapped at the center of ZIP 57239 is Renshaw — loam, somewhat excessively drained.

TextureLoama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter2.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Renshaw-Sioux complex, 2 to 6 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 57239; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Grenville, SD

Summer high82 °Faverage high, July

Winter low4 °Faverage low, January

Hot days5days a year at 90 °F or more

Freezing nights166nights a year at 32 °F or less

Growing degree days2,609base 50 °F — the season’s usable heat

Longest day15 h 41 mindaylight on June 21

Shortest day8 h 42 mindaylight on December 21

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

Precipitation22.5 inper year, rain and melted snow

Snowfall36 inper year; 102 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Waubay Natl Wild Life, SD (6 mi away); precipitation: Waubay Natl Wild Life, SD (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Lake City, SD · 16 mi

South Dakota planting zones →

Questions about 57239

What planting zone is ZIP code 57239?

ZIP code 57239 (Grenville, 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 Grenville, SD?

The median last spring frost (32 °F) near 57239 is May 1; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Waubay Natl Wild Life station.

When is the first frost in Grenville, SD?

The median first fall frost near 57239 is October 12, giving a median frost-free growing season of 164 days.

When should I plant tomatoes in 57239?

Start tomato seeds indoors around Mar 6 – Mar 20 and set transplants outside around May 8 – May 22, one to three weeks after the median last frost.

How much rain and snow does 57239 get?

About 22.5 inches of precipitation a year and 36 inches of snowfall (NOAA 1991–2020 normals, Waubay Natl Wild Life station).

How hot do summers get in Grenville, SD?

The average high peaks at 82 °F in July, with about 5 days a year at 90 °F or more.

What kind of soil does 57239 have?

The USDA soil survey maps Renshaw at the center of ZIP 57239: loam, somewhat excessively drained, pH about 7.0 (neutral).

Did spring come early in Grenville, SD in 2026?

Spring leaf-out near 57239 came on Apr 18 in 2026, about the same as the 1991–2020 average (Apr 20), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Grenville, SD?

Long-day onions: the longest day near 57239 is 15 h 41 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 57239 change?

Yes. The 2012 USDA map put 57239 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.