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

Planting zone for 53012 — Cedarburg, WI

ZIP code 53012 (Cedarburg, Ozaukee County) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is April 23 and the first fall frost October 24.

Where ZIP 53012 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 23

First frostOct 24

2012 zone5b

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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cedarburg, 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 Cedarburg, WI

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 23median — 50% chance of a later frost

Safe for tender plantsMay 9only 10% chance of frost after

First fall frostOctober 24median — 10% chance by Oct 8

Growing season182 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around November 2.

From the NOAA station Grafton Wwtp, WI — 4 miles away, elevation 742 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 53012

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 12 – Mar 26

SpinachSow outdoors · Mar 12 – Apr 2

Broccoli, cabbageStart indoors · Feb 12 – Feb 26

Broccoli, cabbageTransplant · Apr 2 – Apr 16

Onion setsPlant outdoors · Mar 26 – Apr 9

PotatoesPlant outdoors · Apr 2 – Apr 16

LettuceSow outdoors · Mar 26 – Apr 9

Carrots, beetsSow outdoors · Apr 2 – Apr 16

TomatoesStart indoors · Feb 26 – Mar 12

TomatoesTransplant · Apr 30 – May 14

Peppers, eggplantStart indoors · Feb 12 – Feb 26

Peppers, eggplantTransplant · May 7 – May 21

BeansSow outdoors · Apr 30 – May 14

Sweet cornSow outdoors · Apr 30 – May 14

Cucumbers, squashSow outdoors · Apr 30 – May 14

Fall lettuce, spinachSow outdoors · Aug 29 – Sep 12

GarlicPlant cloves · Oct 10 – Nov 14

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 23) and first fall frost (Oct 24) 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 53012 came on Apr 4 — 12 days earlier than the 1991–2020 average (Apr 16).

average
Apr 162026
Apr 4

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 Cedarburg, WI.

Soil in Cedarburg, WI

The soil mapped at the center of ZIP 53012 is Palms — mucky peat, very poorly drained.

TextureMucky peattop layer

DrainageVery poorly drainedconsider raised beds

Organic matter73%high

Hydrologic groupB/Dmoderate when drained; wet otherwise

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Palms mucky peat, 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 53012; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cedarburg, WI

Summer high81 °Faverage high, July

Winter low17 °Faverage low, January

Hot days6days a year at 90 °F or more

Freezing nights134nights a year at 32 °F or less

Growing degree days2,586base 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)

Precipitation35.5 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: Grafton Wwtp, WI (4 mi away); precipitation: Grafton Wwtp, WI (4 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.

Germantown, WI · 7 mi

Wisconsin planting zones →

Questions about 53012

What planting zone is ZIP code 53012?

ZIP code 53012 (Cedarburg, 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 Cedarburg, WI?

The median last spring frost (32 °F) near 53012 is April 23; after May 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Grafton Wwtp station.

When is the first frost in Cedarburg, WI?

The median first fall frost near 53012 is October 24, giving a median frost-free growing season of 182 days.

When should I plant tomatoes in 53012?

Start tomato seeds indoors around Feb 26 – Mar 12 and set transplants outside around Apr 30 – May 14, one to three weeks after the median last frost.

How much rain and snow does 53012 get?

About 35.5 inches of precipitation a year (NOAA 1991–2020 normals, Grafton Wwtp station).

How hot do summers get in Cedarburg, WI?

The average high peaks at 81 °F in July, with about 6 days a year at 90 °F or more.

What kind of soil does 53012 have?

The USDA soil survey maps Palms at the center of ZIP 53012: mucky peat, very poorly drained.

Did spring come early in Cedarburg, WI in 2026?

Spring leaf-out near 53012 came on Apr 4 in 2026, 12 days earlier than the 1991–2020 average (Apr 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cedarburg, WI?

Long-day onions: the longest day near 53012 is 15 h 24 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).