Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 30, 2026

Planting zone for 57779 — Saint Onge, SD

ZIP code 57779 (Saint Onge, Lawrence County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 12 and the first fall frost October 2.

Where ZIP 57779 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostMay 12

First frostOct 2

2012 zone5a

Was 5a 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Saint Onge, 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 Saint Onge, 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 frostOctober 2median — 10% chance by Sep 21

Growing season143 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 30 and returns around October 12.

From the NOAA station Spearfish, SD — 7 miles away, elevation 3,632 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 57779

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 7 – Aug 21

GarlicPlant cloves · Sep 18 – Oct 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 12) and first fall frost (Oct 2) 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 57779 came on Mar 16 — 21 days earlier than the 1991–2020 average (Apr 6).

average
Apr 62026
Mar 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).

Native plants for zone 5b in South Dakota

458 plants native to the lower 48 states, recorded in South Dakota, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. 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 Saint Onge, SD.

Soil in Saint Onge, SD

The soil mapped at the center of ZIP 57779 is Boneek — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.7neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2.9%moderate

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Boneek silt loam, 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 57779; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Saint Onge, SD

Summer high84 °Faverage high, July

Winter low16 °Faverage low, January

Hot days26days a year at 90 °F or more

Freezing nights144nights a year at 32 °F or less

Growing degree days2,333base 50 °F — the season’s usable heat

Longest day15 h 34 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)

Precipitation25.2 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Spearfish, SD (7 mi away); precipitation: Whitewood 4.2 Nnw, SD (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

577935a

Whitewood, SD · 9 mi

577835b

Spearfish, SD · 11 mi

Belle Fourche, SD · 26 mi

South Dakota planting zones →

Questions about 57779

What planting zone is ZIP code 57779?

ZIP code 57779 (Saint Onge, SD) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Saint Onge, SD?

The median last spring frost (32 °F) near 57779 is May 12; after May 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Spearfish station.

When is the first frost in Saint Onge, SD?

The median first fall frost near 57779 is October 2, giving a median frost-free growing season of 143 days.

When should I plant tomatoes in 57779?

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 57779 get?

About 25.2 inches of precipitation a year (NOAA 1991–2020 normals, Whitewood 4.2 Nnw station).

How hot do summers get in Saint Onge, SD?

The average high peaks at 84 °F in July, with about 26 days a year at 90 °F or more.

What kind of soil does 57779 have?

The USDA soil survey maps Boneek at the center of ZIP 57779: silt loam, well drained, pH about 6.7 (neutral).

Did spring come early in Saint Onge, SD in 2026?

Spring leaf-out near 57779 came on Mar 16 in 2026, 21 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Saint Onge, SD?

Long-day onions: the longest day near 57779 is 15 h 34 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 57779 change?

Yes. The 2012 USDA map put 57779 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.