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

Planting zone for Sun Prairie, WI

Sun Prairie, WI is in USDA zone 5a across its 2 ZIP codes. The median last spring frost is May 1 and the first fall frost October 10.

Sun Prairie on the zone map

Outlined: its 1 ZIP code areas · 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
ZIP codes2
Last frostMay 1
First frostOct 10
Growing season160 days

5a 2 ZIPs

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Sun Prairie, 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 Sun Prairie, WI

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 1median — 50% chance of a later frost
Safe for tender plantsMay 16only 10% chance of frost after
First fall frostOctober 10median — 10% chance by Sep 26
Growing season160 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 20 and returns around October 22.

From the NOAA station Madison Dane Regional Airport, WI, elevation 866 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 Sun Prairie

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 20 – Apr 3
SpinachSow outdoors · Mar 20 – Apr 10
Broccoli, cabbageStart indoors · Feb 20 – Mar 6
Broccoli, cabbageTransplant · Apr 10 – Apr 24
Onion setsPlant outdoors · Apr 3 – Apr 17
PotatoesPlant outdoors · Apr 10 – Apr 24
LettuceSow outdoors · Apr 3 – Apr 17
Carrots, beetsSow outdoors · Apr 10 – Apr 24
TomatoesStart indoors · Mar 6 – Mar 20
TomatoesTransplant · May 8 – May 22
Peppers, eggplantStart indoors · Feb 20 – Mar 6
Peppers, eggplantTransplant · May 15 – May 29
BeansSow outdoors · May 8 – May 22
Sweet cornSow outdoors · May 8 – May 22
Cucumbers, squashSow outdoors · May 8 – May 22
Fall lettuce, spinachSow outdoors · Aug 15 – Aug 29
GarlicPlant cloves · Sep 26 – Oct 31
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 1) and first fall frost (Oct 10) 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 53590 came on Mar 30 — 14 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 Sun Prairie, WI.

Soil in Sun Prairie, WI

The soil mapped at the center of ZIP 53590 is Plano — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.7neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter4%moderate
Hydrologic groupBwater soaks in moderately
Farmland classprime farmlandUSDA classification

Map unit: Plano silt loam, till substratum, 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 53590; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sun Prairie, WI

Summer high82 °Faverage high, July
Winter low12 °Faverage low, January
Hot days9days a year at 90 °F or more
Freezing nights147nights a year at 32 °F or less
Growing degree days2,669base 50 °F — the season’s usable heat
Longest day15 h 23 mindaylight on June 21
Shortest day8 h 59 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation37.1 inper year, rain and melted snow
Snowfall52 inper year; 78 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 27 °F, low 12 °F 27°12° JanFebruary: average high 31 °F, low 15 °F 31°15° FebMarch: average high 44 °F, low 25 °F 44°25° MarApril: average high 57 °F, low 36 °F 57°36° AprMay: average high 69 °F, low 47 °F 69°47° MayJune: average high 79 °F, low 57 °F 79°57° JunJuly: average high 82 °F, low 62 °F 82°62° JulAugust: average high 80 °F, low 60 °F 80°60° AugSeptember: average high 73 °F, low 51 °F 73°51° SepOctober: average high 60 °F, low 40 °F 60°40° OctNovember: average high 45 °F, low 29 °F 45°29° NovDecember: average high 32 °F, low 18 °F 32°18° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 1.47 in precipitation, 13.7 in snowfall 1.5❄14 JanFebruary: 1.52 in precipitation, 12.8 in snowfall 1.5❄13 FebMarch: 2.26 in precipitation, 7 in snowfall 2.3❄7 MarApril: 3.78 in precipitation, 2.6 in snowfall 3.8❄3 AprMay: 4.10 in precipitation, 0.1 in snowfall 4.1 MayJune: 5.28 in precipitation 5.3 JunJuly: 4.51 in precipitation 4.5 JulAugust: 4.16 in precipitation 4.2 AugSeptember: 3.43 in precipitation 3.4 SepOctober: 2.77 in precipitation, 0.6 in snowfall 2.8❄1 OctNovember: 2.22 in precipitation, 3 in snowfall 2.2❄3 NovDecember: 1.63 in precipitation, 12 in snowfall 1.6❄12 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Madison Dane Regional Airport, WI (8 mi away); precipitation: Madison Dane Regional Airport, WI (8 mi away). Daylight is calculated from latitude.

ZIP codes in Sun Prairie

535905a
−20 to −15 °F
535965a
−20 to −15 °F

Wisconsin planting zones →

Questions about Sun Prairie

What planting zone is Sun Prairie, WI?

Sun Prairie, WI is in USDA hardiness zone 5a on the 2023 map (5a: −20 to −15 °F).

When is the last frost in Sun Prairie, WI?

The median last spring frost is May 1 and the median first fall frost is October 10 (NOAA 1991–2020 normals, Madison Dane Regional Airport station).

When can I plant a garden in Sun Prairie, WI?

Cool-season crops like peas and spinach go in around Mar 20 – Apr 10; tomatoes, peppers, beans and squash after about May 8, once frost risk has passed.

What kind of onions grow in Sun Prairie, WI?

Long-day onions: the longest day is 15 h 23 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

How much rain and snow does Sun Prairie, WI get?

About 37.1 inches of precipitation a year and 52 inches of snowfall (NOAA 1991–2020 normals).