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

Planting zone for 57201 — Watertown, SD

ZIP code 57201 (Watertown, Codington County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 7 and the first fall frost September 30.

Where ZIP 57201 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 7
First frostSep 30
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 Watertown, 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 Watertown, SD

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 7median — 50% chance of a later frost
Safe for tender plantsMay 20only 10% chance of frost after
First fall frostSeptember 30median — 10% chance by Sep 19
Growing season145 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 29 and returns around October 9.

From the NOAA station Watertown Regional Airport, SD — 4 miles away, elevation 1,749 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 57201

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 26 – Apr 9
SpinachSow outdoors · Mar 26 – Apr 16
Broccoli, cabbageStart indoors · Feb 26 – Mar 12
Broccoli, cabbageTransplant · Apr 16 – Apr 30
Onion setsPlant outdoors · Apr 9 – Apr 23
PotatoesPlant outdoors · Apr 16 – Apr 30
LettuceSow outdoors · Apr 9 – Apr 23
Carrots, beetsSow outdoors · Apr 16 – Apr 30
TomatoesStart indoors · Mar 12 – Mar 26
TomatoesTransplant · May 14 – May 28
Peppers, eggplantStart indoors · Feb 26 – Mar 12
Peppers, eggplantTransplant · May 21 – Jun 4
BeansSow outdoors · May 14 – May 28
Sweet cornSow outdoors · May 14 – May 28
Cucumbers, squashSow outdoors · May 14 – May 28
Fall lettuce, spinachSow outdoors · Aug 5 – Aug 19
GarlicPlant cloves · Sep 16 – Oct 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 7) and first fall frost (Sep 30) 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 57201 came on Apr 19 — about the same time as the 1991–2020 average (Apr 20).

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).

Soil in Watertown, SD

The soil mapped at the center of ZIP 57201 is Doburg — loam, well drained.

TextureLoama good balance for most vegetables
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Doburg-Forestville 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 57201; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Watertown, SD

Summer high82 °Faverage high, July
Winter low3 °Faverage low, January
Hot days9days a year at 90 °F or more
Freezing nights174nights a year at 32 °F or less
Growing degree days2,370base 50 °F — the season’s usable heat
Longest day15 h 37 mindaylight on June 21
Shortest day8 h 46 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation24.8 inper year, rain and melted snow

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 21 °F, low 3 °F 21°3° JanFebruary: average high 26 °F, low 7 °F 26°7° FebMarch: average high 39 °F, low 20 °F 39°20° MarApril: average high 54 °F, low 32 °F 54°32° AprMay: average high 67 °F, low 45 °F 67°45° MayJune: average high 77 °F, low 55 °F 77°55° JunJuly: average high 82 °F, low 60 °F 82°60° JulAugust: average high 80 °F, low 58 °F 80°58° AugSeptember: average high 72 °F, low 49 °F 72°49° SepOctober: average high 56 °F, low 35 °F 56°35° OctNovember: average high 40 °F, low 21 °F 40°21° NovDecember: average high 26 °F, low 9 °F 26°9° Dec

Precipitation by month inches

0″1″2″3″4″January: 0.64 in precipitation 0.6 JanFebruary: 0.70 in precipitation 0.7 FebMarch: 1.08 in precipitation 1.1 MarApril: 2.25 in precipitation 2.3 AprMay: 3.23 in precipitation 3.2 MayJune: 3.82 in precipitation 3.8 JunJuly: 3.51 in precipitation 3.5 JulAugust: 2.97 in precipitation 3.0 AugSeptember: 2.81 in precipitation 2.8 SepOctober: 2.22 in precipitation 2.2 OctNovember: 0.84 in precipitation 0.8 NovDecember: 0.75 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Watertown Regional Airport, SD (4 mi away); precipitation: Watertown 1w, SD (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

572454b
Kranzburg, SD · 9 mi
572384b
Goodwin, SD · 12 mi
572354b
Florence, SD · 15 mi
572634b
South Shore, SD · 15 mi
572654b
Strandburg, SD · 16 mi
572234a
Castlewood, SD · 16 mi
572424b
Hazel, SD · 17 mi
572434b
Henry, SD · 17 mi

South Dakota planting zones →

Questions about 57201

What planting zone is ZIP code 57201?

ZIP code 57201 (Watertown, 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 Watertown, SD?

The median last spring frost (32 °F) near 57201 is May 7; after May 20 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Watertown Regional Airport station.

When is the first frost in Watertown, SD?

The median first fall frost near 57201 is September 30, giving a median frost-free growing season of 145 days.

When should I plant tomatoes in 57201?

Start tomato seeds indoors around Mar 12 – Mar 26 and set transplants outside around May 14 – May 28, one to three weeks after the median last frost.

How much rain and snow does 57201 get?

About 24.8 inches of precipitation a year (NOAA 1991–2020 normals, Watertown 1w station).

How hot do summers get in Watertown, SD?

The average high peaks at 82 °F in July, with about 9 days a year at 90 °F or more.

What kind of soil does 57201 have?

The USDA soil survey maps Doburg at the center of ZIP 57201: loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Watertown, SD in 2026?

Spring leaf-out near 57201 came on Apr 19 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 Watertown, SD?

Long-day onions: the longest day near 57201 is 15 h 37 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).