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

Planting zone for 57039 — Lennox, SD

ZIP code 57039 (Lennox, Lincoln County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 2 and the first fall frost October 2.

Where ZIP 57039 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.

Zone5a−20 to −15 °F

Coldest night−28.9 to −26.1 °C

Last frostMay 2

First frostOct 2

2012 zone4b

Was 4b 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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Lennox, 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 Lennox, SD

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 2median — 50% chance of a later frost

Safe for tender plantsMay 15only 10% chance of frost after

First fall frostOctober 2median — 10% chance by Sep 19

Growing season151 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 23 and returns around October 11.

From the NOAA station Canton, SD — 14 miles away, elevation 1,316 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 57039

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 21 – Apr 4

SpinachSow outdoors · Mar 21 – Apr 11

Broccoli, cabbageStart indoors · Feb 21 – Mar 7

Broccoli, cabbageTransplant · Apr 11 – Apr 25

Onion setsPlant outdoors · Apr 4 – Apr 18

PotatoesPlant outdoors · Apr 11 – Apr 25

LettuceSow outdoors · Apr 4 – Apr 18

Carrots, beetsSow outdoors · Apr 11 – Apr 25

TomatoesStart indoors · Mar 7 – Mar 21

TomatoesTransplant · May 9 – May 23

Peppers, eggplantStart indoors · Feb 21 – Mar 7

Peppers, eggplantTransplant · May 16 – May 30

BeansSow outdoors · May 9 – May 23

Sweet cornSow outdoors · May 9 – May 23

Cucumbers, squashSow outdoors · May 9 – May 23

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 2) 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 57039 came on Mar 25 — 18 days earlier than the 1991–2020 average (Apr 12).

average
Apr 122026
Mar 25

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 5a in South Dakota

452 plants native to the lower 48 states, recorded in South Dakota, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. 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 Lennox, SD.

Soil in Lennox, SD

The soil mapped at the center of ZIP 57039 is Wentworth — silty clay loam, moderately well drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up

pH6.5neutral; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter4.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classPrime farmland if drainedUSDA classification

Map unit: Wentworth-Chancellor silty clay loams, 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 57039; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lennox, SD

Summer high83 °Faverage high, July

Winter low6 °Faverage low, January

Hot days15days a year at 90 °F or more

Freezing nights160nights a year at 32 °F or less

Growing degree days2,727base 50 °F — the season’s usable heat

Longest day15 h 24 mindaylight on June 21

Shortest day8 h 58 mindaylight on December 21

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

Precipitation28.2 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: Canton, SD (14 mi away); precipitation: Hurley 0.2 S, SD (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

Chancellor, SD · 8 mi

570645a

Tea, SD · 8 mi

570325a

Harrisburg, SD · 12 mi

571065a

Sioux Falls, SD · 12 mi

571085a

Sioux Falls, SD · 13 mi

570135a

Canton, SD · 13 mi

South Dakota planting zones →

Questions about 57039

What planting zone is ZIP code 57039?

ZIP code 57039 (Lennox, SD) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Lennox, SD?

The median last spring frost (32 °F) near 57039 is May 2; after May 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Canton station.

When is the first frost in Lennox, SD?

The median first fall frost near 57039 is October 2, giving a median frost-free growing season of 151 days.

When should I plant tomatoes in 57039?

Start tomato seeds indoors around Mar 7 – Mar 21 and set transplants outside around May 9 – May 23, one to three weeks after the median last frost.

How much rain and snow does 57039 get?

About 28.2 inches of precipitation a year (NOAA 1991–2020 normals, Hurley 0.2 S station).

How hot do summers get in Lennox, SD?

The average high peaks at 83 °F in July, with about 15 days a year at 90 °F or more.

What kind of soil does 57039 have?

The USDA soil survey maps Wentworth at the center of ZIP 57039: silty clay loam, moderately well drained, pH about 6.5 (neutral).

Did spring come early in Lennox, SD in 2026?

Spring leaf-out near 57039 came on Mar 25 in 2026, 18 days earlier than the 1991–2020 average (Apr 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Lennox, SD?

Long-day onions: the longest day near 57039 is 15 h 24 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 57039 change?

Yes. The 2012 USDA map put 57039 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.