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

Planting zone for 50585 — Sioux Rapids, IA

ZIP code 50585 (Sioux Rapids, Buena Vista County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 30 and the first fall frost October 5.

Where ZIP 50585 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 frostApr 30
First frostOct 5
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 Sioux Rapids, IA…

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 Sioux Rapids, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 30median — 50% chance of a later frost
Safe for tender plantsMay 11only 10% chance of frost after
First fall frostOctober 5median — 10% chance by Sep 22
Growing season159 daysfrost-free, median

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

From the NOAA station Sioux Rapids 4 E, IA — 4 miles away, elevation 1,421 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 50585

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 19 – Apr 2
SpinachSow outdoors · Mar 19 – Apr 9
Broccoli, cabbageStart indoors · Feb 19 – Mar 5
Broccoli, cabbageTransplant · Apr 9 – Apr 23
Onion setsPlant outdoors · Apr 2 – Apr 16
PotatoesPlant outdoors · Apr 9 – Apr 23
LettuceSow outdoors · Apr 2 – Apr 16
Carrots, beetsSow outdoors · Apr 9 – Apr 23
TomatoesStart indoors · Mar 5 – Mar 19
TomatoesTransplant · May 7 – May 21
Peppers, eggplantStart indoors · Feb 19 – Mar 5
Peppers, eggplantTransplant · May 14 – May 28
BeansSow outdoors · May 7 – May 21
Sweet cornSow outdoors · May 7 – May 21
Cucumbers, squashSow outdoors · May 7 – May 21
Fall lettuce, spinachSow outdoors · Aug 10 – Aug 24
GarlicPlant cloves · Sep 21 – Oct 26
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 5) 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 50585 came on Mar 25 — 17 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 5a in Iowa

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

Trees 46

American basswood100 ft · blooms late spring · low shade tolerance · to −46 °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 °Fbalsam fir60 ft · blooms mid summer · low shade tolerance · to −43 °F

Shrubs 77

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 185

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 133

arctic brome3 ft · blooms early summer · low shade tolerance · to −33 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low shade tolerance · to −38 °FBicknell's sedge3 ft · blooms late spring · low shade tolerance · to −38 °Fbig bluestem6 ft · blooms summer · high shade tolerance · to −46 °Fblue grama1 ft · blooms early summer · high shade tolerance · to −43 °F

Vines 7

American bittersweet15 ft · blooms spring · low shade tolerance · to −38 °Fdevil's darning needles15 ft · blooms mid summer · medium shade tolerance · to −38 °Ffrost grape83 ft · blooms late spring · medium shade tolerance · to −23 °Friverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Fsummer grape30 ft · blooms late spring · low shade tolerance · to −23 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Sioux Rapids, IA.

Soil in Sioux Rapids, IA

The soil mapped at the center of ZIP 50585 is McCreath — silty clay loam, somewhat poorly drained.

TextureSilty clay loamholds water and nutrients; slow to drain and warm up
pH6.5neutral; most vegetables like 6.0–7.0
DrainageSomewhat poorly drainedconsider raised beds
Organic matter5.5%high
Hydrologic groupC/Dslow when drained; wet otherwise
Farmland classprime farmlandUSDA classification

Map unit: McCreath silty clay loam, 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 50585; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sioux Rapids, IA

Summer high82 °Faverage high, July
Winter low8 °Faverage low, January
Hot days11days a year at 90 °F or more
Freezing nights157nights a year at 32 °F or less
Growing degree days2,777base 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)
Precipitation32 inper year, rain and melted snow
Snowfall35 inper year; 77 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 25 °F, low 8 °F 25°8° JanFebruary: average high 30 °F, low 13 °F 30°13° FebMarch: average high 43 °F, low 25 °F 43°25° MarApril: average high 58 °F, low 36 °F 58°36° AprMay: average high 70 °F, low 48 °F 70°48° MayJune: average high 80 °F, low 59 °F 80°59° JunJuly: average high 82 °F, low 62 °F 82°62° JulAugust: average high 79 °F, low 59 °F 79°59° AugSeptember: average high 74 °F, low 51 °F 74°51° SepOctober: average high 61 °F, low 39 °F 61°39° OctNovember: average high 44 °F, low 25 °F 44°25° NovDecember: average high 30 °F, low 14 °F 30°14° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″6″January: 0.62 in precipitation, 8 in snowfall 0.6❄8 JanFebruary: 0.83 in precipitation, 6.9 in snowfall 0.8❄7 FebMarch: 1.76 in precipitation, 6.5 in snowfall 1.8❄7 MarApril: 3.58 in precipitation, 2.3 in snowfall 3.6❄2 AprMay: 4.19 in precipitation, 0.3 in snowfall 4.2 MayJune: 5.05 in precipitation 5.0 JunJuly: 3.29 in precipitation 3.3 JulAugust: 4.41 in precipitation 4.4 AugSeptember: 3.39 in precipitation 3.4 SepOctober: 2.51 in precipitation, 0.7 in snowfall 2.5❄1 OctNovember: 1.42 in precipitation, 3.8 in snowfall 1.4❄4 NovDecember: 0.94 in precipitation, 6.7 in snowfall 0.9❄7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Sioux Rapids 4 E, IA (4 mi away); precipitation: Sioux Rapids 4 E, IA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

510335a
Linn Grove, IA · 6 mi
513435a
Greenville, IA · 7 mi
513665a
Webb, IA · 8 mi
505765a
Rembrandt, IA · 8 mi
505655a
Marathon, IA · 8 mi
513415a
Gillett Grove, IA · 9 mi
510475a
Peterson, IA · 12 mi
513575a
Royal, IA · 12 mi

Iowa planting zones →

Questions about 50585

What planting zone is ZIP code 50585?

ZIP code 50585 (Sioux Rapids, IA) 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 Sioux Rapids, IA?

The median last spring frost (32 °F) near 50585 is April 30; after May 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Sioux Rapids 4 E station.

When is the first frost in Sioux Rapids, IA?

The median first fall frost near 50585 is October 5, giving a median frost-free growing season of 159 days.

When should I plant tomatoes in 50585?

Start tomato seeds indoors around Mar 5 – Mar 19 and set transplants outside around May 7 – May 21, one to three weeks after the median last frost.

How much rain and snow does 50585 get?

About 32 inches of precipitation a year and 35 inches of snowfall (NOAA 1991–2020 normals, Sioux Rapids 4 E station).

How hot do summers get in Sioux Rapids, IA?

The average high peaks at 82 °F in July, with about 11 days a year at 90 °F or more.

What kind of soil does 50585 have?

The USDA soil survey maps McCreath at the center of ZIP 50585: silty clay loam, somewhat poorly drained, pH about 6.5 (neutral).

Did spring come early in Sioux Rapids, IA in 2026?

Spring leaf-out near 50585 came on Mar 25 in 2026, 17 days earlier than the 1991–2020 average (Apr 11), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Sioux Rapids, IA?

Long-day onions: the longest day near 50585 is 15 h 21 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).