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

Planting zone for 53237 — Milwaukee, WI

ZIP code 53237 (Milwaukee, Milwaukee County) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is April 26 and the first fall frost October 22.

Where ZIP 53237 is

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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostApr 26
First frostOct 22
2012 zone5b

Was 5b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Milwaukee, 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 Milwaukee, WI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 26median — 50% chance of a later frost
Safe for tender plantsMay 12only 10% chance of frost after
First fall frostOctober 22median — 10% chance by Oct 7
Growing season177 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 14 and returns around November 1.

From the NOAA station West Allis, WI — 5 miles away, elevation 722 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 53237

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 15 – Mar 29
SpinachSow outdoors · Mar 15 – Apr 5
Broccoli, cabbageStart indoors · Feb 15 – Mar 1
Broccoli, cabbageTransplant · Apr 5 – Apr 19
Onion setsPlant outdoors · Mar 29 – Apr 12
PotatoesPlant outdoors · Apr 5 – Apr 19
LettuceSow outdoors · Mar 29 – Apr 12
Carrots, beetsSow outdoors · Apr 5 – Apr 19
TomatoesStart indoors · Mar 1 – Mar 15
TomatoesTransplant · May 3 – May 17
Peppers, eggplantStart indoors · Feb 15 – Mar 1
Peppers, eggplantTransplant · May 10 – May 24
BeansSow outdoors · May 3 – May 17
Sweet cornSow outdoors · May 3 – May 17
Cucumbers, squashSow outdoors · May 3 – May 17
Fall lettuce, spinachSow outdoors · Aug 27 – Sep 10
GarlicPlant cloves · Oct 8 – Nov 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 26) and first fall frost (Oct 22) 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 53237 came on Mar 30 — 12 days earlier than the 1991–2020 average (Apr 11).

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 6a in Wisconsin

526 plants native to the lower 48 states, recorded in Wisconsin, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 49

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °FAmerican beech80 ft · blooms mid spring · low shade tolerance · to −44 °FAmerican chestnut115 ft · blooms early summer · high shade tolerance · to −33 °FAmerican elm120 ft · blooms early spring · medium shade tolerance · to −46 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Farborvitae50 ft · blooms mid spring · medium shade tolerance · to −33 °F

Shrubs 94

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falternateleaf dogwood25 ft · blooms mid spring · low shade tolerance · to −47 °FAmerican black currant3 ft · blooms early spring · to −46 °FAmerican hazelnut10 ft · blooms spring · medium shade tolerance · to −33 °FAmerican hornbeam30 ft · blooms mid spring · low shade tolerance · to −34 °F

Wildflowers & perennials 200

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °FAmerican bur-reed3 ft · blooms indeterminate · medium shade tolerance · to −33 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °FAmerican licorice4 ft · blooms late spring · medium shade tolerance · to −38 °FAmerican lotus3 ft · blooms mid summer · high shade tolerance · to −36 °FAmerican pokeweed7 ft · blooms mid summer · low shade tolerance · to −33 °F

Grasses 161

American beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °Farctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °Fbeaked spikerush3 ft · blooms late spring · high shade tolerance · to −28 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °F

Vines 6

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °FVirginia creeper1 ft · blooms late spring · medium shade tolerance · to −28 °F

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 Milwaukee, WI.

Soil in Milwaukee, WI

The center of ZIP 53237 is mapped as No Digital Data Available: built-over ground without natural soil data. Garden soil here is usually imported or disturbed — test before you plant.

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 53237; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Milwaukee, WI

Summer high85 °Faverage high, July
Winter low15 °Faverage low, January
Hot days18days a year at 90 °F or more
Freezing nights133nights a year at 32 °F or less
Growing degree days3,001base 50 °F — the season’s usable heat
Longest day15 h 22 mindaylight on June 21
Shortest day9 h 00 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation35.2 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 31 °F, low 15 °F 31°15° JanFebruary: average high 34 °F, low 17 °F 34°17° FebMarch: average high 45 °F, low 27 °F 45°27° MarApril: average high 57 °F, low 37 °F 57°37° AprMay: average high 70 °F, low 48 °F 70°48° MayJune: average high 80 °F, low 58 °F 80°58° JunJuly: average high 85 °F, low 63 °F 85°63° JulAugust: average high 83 °F, low 62 °F 83°62° AugSeptember: average high 77 °F, low 54 °F 77°54° SepOctober: average high 62 °F, low 42 °F 62°42° OctNovember: average high 48 °F, low 30 °F 48°30° NovDecember: average high 36 °F, low 21 °F 36°21° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 1.66 in precipitation 1.7 JanFebruary: 1.54 in precipitation 1.5 FebMarch: 1.98 in precipitation 2.0 MarApril: 3.56 in precipitation 3.6 AprMay: 3.59 in precipitation 3.6 MayJune: 5.03 in precipitation 5.0 JunJuly: 3.79 in precipitation 3.8 JulAugust: 3.81 in precipitation 3.8 AugSeptember: 3.31 in precipitation 3.3 SepOctober: 3.10 in precipitation 3.1 OctNovember: 2.01 in precipitation 2.0 NovDecember: 1.85 in precipitation 1.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: West Allis, WI (5 mi away); precipitation: Shorewood 0.6 Nw, WI (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6a.

532016a
Milwaukee, WI · <1 mi
532346a
Milwaukee, WI · <1 mi
532746a
Milwaukee, WI · <1 mi
532886a
Milwaukee, WI · <1 mi
532786a
Milwaukee, WI · <1 mi
532596a
Milwaukee, WI · <1 mi
532906a
Milwaukee, WI · <1 mi
532036a
Milwaukee, WI · <1 mi

All 39 ZIP codes in Milwaukee → · Wisconsin planting zones →

Questions about 53237

What planting zone is ZIP code 53237?

ZIP code 53237 (Milwaukee, WI) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Milwaukee, WI?

The median last spring frost (32 °F) near 53237 is April 26; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, West Allis station.

When is the first frost in Milwaukee, WI?

The median first fall frost near 53237 is October 22, giving a median frost-free growing season of 177 days.

When should I plant tomatoes in 53237?

Start tomato seeds indoors around Mar 1 – Mar 15 and set transplants outside around May 3 – May 17, one to three weeks after the median last frost.

How much rain and snow does 53237 get?

About 35.2 inches of precipitation a year (NOAA 1991–2020 normals, Shorewood 0.6 Nw station).

How hot do summers get in Milwaukee, WI?

The average high peaks at 85 °F in July, with about 18 days a year at 90 °F or more.

Did spring come early in Milwaukee, WI in 2026?

Spring leaf-out near 53237 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 Milwaukee, WI?

Long-day onions: the longest day near 53237 is 15 h 22 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 53237 change?

Yes. The 2012 USDA map put 53237 in zone 5b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.