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

Planting zone for 53526 — Cobb, WI

ZIP code 53526 (Cobb, Iowa County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 3 and the first fall frost October 7.

Where ZIP 53526 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 3
First frostOct 7
2012 zone5a

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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cobb, 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 Cobb, WI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 3median — 50% chance of a later frost
Safe for tender plantsMay 17only 10% chance of frost after
First fall frostOctober 7median — 10% chance by Sep 25
Growing season157 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 22 and returns around October 18.

From the NOAA station Dodgeville Wwtp, WI — 12 miles away, elevation 1,119 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 53526

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 22 – Apr 5
SpinachSow outdoors · Mar 22 – Apr 12
Broccoli, cabbageStart indoors · Feb 22 – Mar 8
Broccoli, cabbageTransplant · Apr 12 – Apr 26
Onion setsPlant outdoors · Apr 5 – Apr 19
PotatoesPlant outdoors · Apr 12 – Apr 26
LettuceSow outdoors · Apr 5 – Apr 19
Carrots, beetsSow outdoors · Apr 12 – Apr 26
TomatoesStart indoors · Mar 8 – Mar 22
TomatoesTransplant · May 10 – May 24
Peppers, eggplantStart indoors · Feb 22 – Mar 8
Peppers, eggplantTransplant · May 17 – May 31
BeansSow outdoors · May 10 – May 24
Sweet cornSow outdoors · May 10 – May 24
Cucumbers, squashSow outdoors · May 10 – May 24
Fall lettuce, spinachSow outdoors · Aug 12 – Aug 26
GarlicPlant cloves · Sep 23 – Oct 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 3) and first fall frost (Oct 7) 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 53526 came on Mar 28 — 16 days earlier than the 1991–2020 average (Apr 13).

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 Wisconsin

510 plants native to the lower 48 states, recorded in Wisconsin, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. Each links to its USDA PLANTS profile.

Trees 48

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 93

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 191

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 158

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 5

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 °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 Cobb, WI.

Soil in Cobb, WI

The soil mapped at the center of ZIP 53526 is Tama — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3.5%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Tama silt loam, driftless, 2 to 6 percent slopes, moderately eroded.

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 53526; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cobb, WI

Summer high81 °Faverage high, July
Winter low9 °Faverage low, January
Hot days6days a year at 90 °F or more
Freezing nights160nights a year at 32 °F or less
Growing degree days2,485base 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)
Precipitation39.6 inper year, rain and melted snow
Snowfall41 inper year; 81 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 26 °F, low 9 °F 26°9° JanFebruary: average high 31 °F, low 12 °F 31°12° FebMarch: average high 43 °F, low 23 °F 43°23° MarApril: average high 57 °F, low 34 °F 57°34° AprMay: average high 68 °F, low 46 °F 68°46° MayJune: average high 78 °F, low 56 °F 78°56° JunJuly: average high 81 °F, low 60 °F 81°60° JulAugust: average high 80 °F, low 58 °F 80°58° AugSeptember: average high 72 °F, low 49 °F 72°49° SepOctober: average high 59 °F, low 38 °F 59°38° OctNovember: average high 44 °F, low 26 °F 44°26° NovDecember: average high 31 °F, low 16 °F 31°16° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 1.45 in precipitation, 10.3 in snowfall 1.4❄10 JanFebruary: 1.52 in precipitation, 10.6 in snowfall 1.5❄11 FebMarch: 2.30 in precipitation, 5.9 in snowfall 2.3❄6 MarApril: 3.88 in precipitation, 1.5 in snowfall 3.9❄2 AprMay: 4.61 in precipitation 4.6 MayJune: 5.73 in precipitation 5.7 JunJuly: 4.71 in precipitation 4.7 JulAugust: 4.39 in precipitation 4.4 AugSeptember: 3.66 in precipitation 3.7 SepOctober: 3.08 in precipitation, 0.6 in snowfall 3.1❄1 OctNovember: 2.47 in precipitation, 1.9 in snowfall 2.5❄2 NovDecember: 1.83 in precipitation, 10.3 in snowfall 1.8❄10 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Dodgeville Wwtp, WI (12 mi away); precipitation: Dodgeville Wwtp, WI (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

535355a
Edmund, WI · 4 mi
535695a
Montfort, WI · 5 mi
535535a
Linden, WI · 5 mi
535435a
Highland, WI · 6 mi
535545a
Livingston, WI · 7 mi
535805a
Rewey, WI · 8 mi
535335a
Dodgeville, WI · 9 mi
535955a
Dodgeville, WI · 10 mi

Wisconsin planting zones →

Questions about 53526

What planting zone is ZIP code 53526?

ZIP code 53526 (Cobb, WI) 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 Cobb, WI?

The median last spring frost (32 °F) near 53526 is May 3; after May 17 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Dodgeville Wwtp station.

When is the first frost in Cobb, WI?

The median first fall frost near 53526 is October 7, giving a median frost-free growing season of 157 days.

When should I plant tomatoes in 53526?

Start tomato seeds indoors around Mar 8 – Mar 22 and set transplants outside around May 10 – May 24, one to three weeks after the median last frost.

How much rain and snow does 53526 get?

About 39.6 inches of precipitation a year and 41 inches of snowfall (NOAA 1991–2020 normals, Dodgeville Wwtp station).

How hot do summers get in Cobb, 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 53526 have?

The USDA soil survey maps Tama at the center of ZIP 53526: silt loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Cobb, WI in 2026?

Spring leaf-out near 53526 came on Mar 28 in 2026, 16 days earlier than the 1991–2020 average (Apr 13), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Cobb, WI?

Long-day onions: the longest day near 53526 is 15 h 22 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).