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

Planting zone for 53538 — Fort Atkinson, WI

ZIP code 53538 (Fort Atkinson, Jefferson County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 28 and the first fall frost October 13.

Where ZIP 53538 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 frostApr 28

First frostOct 13

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 Fort Atkinson, WI…

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 Fort Atkinson, WI

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 28median — 50% chance of a later frost

Safe for tender plantsMay 17only 10% chance of frost after

First fall frostOctober 13median — 10% chance by Sep 29

Growing season166 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 24.

From the NOAA station Ft Atkinson, WI — within 1 mile, elevation 801 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 53538

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 17 – Mar 31

SpinachSow outdoors · Mar 17 – Apr 7

Broccoli, cabbageStart indoors · Feb 17 – Mar 3

Broccoli, cabbageTransplant · Apr 7 – Apr 21

Onion setsPlant outdoors · Mar 31 – Apr 14

PotatoesPlant outdoors · Apr 7 – Apr 21

LettuceSow outdoors · Mar 31 – Apr 14

Carrots, beetsSow outdoors · Apr 7 – Apr 21

TomatoesStart indoors · Mar 3 – Mar 17

TomatoesTransplant · May 5 – May 19

Peppers, eggplantStart indoors · Feb 17 – Mar 3

Peppers, eggplantTransplant · May 12 – May 26

BeansSow outdoors · May 5 – May 19

Sweet cornSow outdoors · May 5 – May 19

Cucumbers, squashSow outdoors · May 5 – May 19

Fall lettuce, spinachSow outdoors · Aug 18 – Sep 1

GarlicPlant cloves · Sep 29 – Nov 3

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 13) 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 53538 came on Mar 30 — 12 days earlier than the 1991–2020 average (Apr 11).

average
Apr 112026
Mar 30

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 Wisconsin

518 plants native to the lower 48 states, recorded in Wisconsin, 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 Fort Atkinson, WI.

Soil in Fort Atkinson, WI

The soil mapped at the center of ZIP 53538 is Kidder — sandy loam, well drained.

TextureSandy loamdrains and warms fast; dries out and needs more feeding

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classprime farmlandUSDA classification

Map unit: Kidder sandy 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 53538; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fort Atkinson, WI

Summer high83 °Faverage high, July

Winter low11 °Faverage low, January

Hot days11days a year at 90 °F or more

Freezing nights146nights a year at 32 °F or less

Growing degree days2,751base 50 °F — the season’s usable heat

Longest day15 h 21 mindaylight on June 21

Shortest day9 h 01 mindaylight on December 21

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

Precipitation35.5 inper year, rain and melted snow

Snowfall36 inper year; 65 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: Ft Atkinson, WI (within 1 mile); precipitation: Ft Atkinson, WI (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5b.

Cambridge, WI · 10 mi

531905b

Whitewater, WI · 10 mi

535345b

Edgerton, WI · 12 mi

535515b

Lake Mills, WI · 12 mi

531375b

Helenville, WI · 12 mi

530385b

Johnson Creek, WI · 13 mi

Wisconsin planting zones →

Questions about 53538

What planting zone is ZIP code 53538?

ZIP code 53538 (Fort Atkinson, WI) 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 Fort Atkinson, WI?

The median last spring frost (32 °F) near 53538 is April 28; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ft Atkinson station.

When is the first frost in Fort Atkinson, WI?

The median first fall frost near 53538 is October 13, giving a median frost-free growing season of 166 days.

When should I plant tomatoes in 53538?

Start tomato seeds indoors around Mar 3 – Mar 17 and set transplants outside around May 5 – May 19, one to three weeks after the median last frost.

How much rain and snow does 53538 get?

About 35.5 inches of precipitation a year and 36 inches of snowfall (NOAA 1991–2020 normals, Ft Atkinson station).

How hot do summers get in Fort Atkinson, WI?

The average high peaks at 83 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 53538 have?

The USDA soil survey maps Kidder at the center of ZIP 53538: sandy loam, well drained, pH about 7.0 (neutral).

Did spring come early in Fort Atkinson, WI in 2026?

Spring leaf-out near 53538 came on Mar 30 in 2026, 12 days earlier than the 1991–2020 average (Apr 11), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Fort Atkinson, WI?

Long-day onions: the longest day near 53538 is 15 h 21 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 53538 change?

Yes. The 2012 USDA map put 53538 in zone 5a; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.