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

Planting zone for 50466 — Riceville, IA

ZIP code 50466 (Riceville, Howard County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is April 30 and the first fall frost October 9.

Where ZIP 50466 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.

Zone4b−25 to −20 °F
Coldest night−31.7 to −28.9 °C
Last frostApr 30
First frostOct 9
2012 zone4b

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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Riceville, 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 Riceville, 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 12only 10% chance of frost after
First fall frostOctober 9median — 10% chance by Sep 25
Growing season163 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 17 and returns around October 20.

From the NOAA station Osage, IA — 16 miles away, elevation 1,171 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 50466

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 14 – Aug 28
GarlicPlant cloves · Sep 25 – Oct 30
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 30) and first fall frost (Oct 9) 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 50466 came on Mar 30 — 17 days earlier than the 1991–2020 average (Apr 16).

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 4b in Iowa

426 plants native to the lower 48 states, recorded in Iowa, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. Each links to its USDA PLANTS profile.

Trees 43

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 72

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 169

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 124

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 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 °Ftrumpet honeysuckle16 ft · blooms late summer · low shade tolerance · to −33 °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 Riceville, IA.

Soil in Riceville, IA

The soil mapped at the center of ZIP 50466 is Bassett — loam, moderately well drained.

TextureLoama good balance for most vegetables
pH6.2slightly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter2.4%moderate
Hydrologic groupCwater soaks in slowly
Farmland classprime farmlandUSDA classification

Map unit: Bassett loam, 2 to 5 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 50466; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Riceville, IA

Summer high81 °Faverage high, July
Winter low6 °Faverage low, January
Hot days8days a year at 90 °F or more
Freezing nights156nights a year at 32 °F or less
Growing degree days2,618base 50 °F — the season’s usable heat
Longest day15 h 25 mindaylight on June 21
Shortest day8 h 57 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation38.1 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°32 °FJanuary: average high 23 °F, low 6 °F 23°6° JanFebruary: average high 28 °F, low 10 °F 28°10° FebMarch: average high 41 °F, low 23 °F 41°23° MarApril: average high 56 °F, low 35 °F 56°35° AprMay: average high 68 °F, low 47 °F 68°47° MayJune: average high 78 °F, low 58 °F 78°58° JunJuly: average high 81 °F, low 62 °F 81°62° JulAugust: average high 79 °F, low 59 °F 79°59° AugSeptember: average high 73 °F, low 50 °F 73°50° SepOctober: average high 60 °F, low 38 °F 60°38° OctNovember: average high 43 °F, low 25 °F 43°25° NovDecember: average high 29 °F, low 14 °F 29°14° Dec

Precipitation by month inches

0″1″2″3″4″5″6″January: 1.02 in precipitation 1.0 JanFebruary: 1.03 in precipitation 1.0 FebMarch: 2.02 in precipitation 2.0 MarApril: 3.77 in precipitation 3.8 AprMay: 5.20 in precipitation 5.2 MayJune: 5.89 in precipitation 5.9 JunJuly: 4.86 in precipitation 4.9 JulAugust: 4.50 in precipitation 4.5 AugSeptember: 3.80 in precipitation 3.8 SepOctober: 2.88 in precipitation 2.9 OctNovember: 1.81 in precipitation 1.8 NovDecember: 1.37 in precipitation 1.4 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Osage, IA (16 mi away); precipitation: Elma, IA (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

3 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

504555a
Mc Intire, IA · 7 mi
521344b
Chester, IA · 9 mi
504545a
Little Cedar, IA · 10 mi
559514b
Le Roy, MN · 10 mi
506284b
Elma, IA · 11 mi
504765a
Stacyville, IA · 12 mi
521554b
Lime Springs, IA · 12 mi
559774b
Taopi, MN · 13 mi

Iowa planting zones →

Questions about 50466

What planting zone is ZIP code 50466?

ZIP code 50466 (Riceville, IA) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Riceville, IA?

The median last spring frost (32 °F) near 50466 is April 30; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Osage station.

When is the first frost in Riceville, IA?

The median first fall frost near 50466 is October 9, giving a median frost-free growing season of 163 days.

When should I plant tomatoes in 50466?

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 50466 get?

About 38.1 inches of precipitation a year (NOAA 1991–2020 normals, Elma station).

How hot do summers get in Riceville, IA?

The average high peaks at 81 °F in July, with about 8 days a year at 90 °F or more.

What kind of soil does 50466 have?

The USDA soil survey maps Bassett at the center of ZIP 50466: loam, moderately well drained, pH about 6.2 (slightly acidic).

Did spring come early in Riceville, IA in 2026?

Spring leaf-out near 50466 came on Mar 30 in 2026, 17 days earlier than the 1991–2020 average (Apr 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Riceville, IA?

Long-day onions: the longest day near 50466 is 15 h 25 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).