Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 50586 — Somers, IA

ZIP code 50586 (Somers, Calhoun County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 26 and the first fall frost October 10.

Where ZIP 50586 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 26

First frostOct 10

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 Somers, 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 Somers, IA

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 6only 10% chance of frost after

First fall frostOctober 10median — 10% chance by Sep 27

Growing season167 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 21.

From the NOAA station Rockwell City, IA — 11 miles away, elevation 1,214 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 50586

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 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 (Apr 26) 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 50586 came on Mar 25 — 15 days earlier than the 1991–2020 average (Apr 9).

average
Apr 92026
Mar 25

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.

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 Somers, IA.

Soil in Somers, IA

The soil mapped at the center of ZIP 50586 is Clarion — 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 matter3.5%moderate

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Clarion loam, 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 50586; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Somers, IA

Summer high83 °Faverage high, July

Winter low8 °Faverage low, January

Hot days13days a year at 90 °F or more

Freezing nights154nights a year at 32 °F or less

Growing degree days2,888base 50 °F — the season’s usable heat

Longest day15 h 17 mindaylight on June 21

Shortest day9 h 04 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation33.8 inper year, rain and melted snow

Snowfall32 inper year; 74 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

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

Nearby ZIP codes

All 8 nearest ZIP codes share zone 5a.

Farnhamville, IA · 9 mi

505635a

Manson, IA · 9 mi

505795a

Rockwell City, IA · 11 mi

505435a

Gowrie, IA · 11 mi

Iowa planting zones →

Questions about 50586

What planting zone is ZIP code 50586?

ZIP code 50586 (Somers, 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 Somers, IA?

The median last spring frost (32 °F) near 50586 is April 26; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Rockwell City station.

When is the first frost in Somers, IA?

The median first fall frost near 50586 is October 10, giving a median frost-free growing season of 167 days.

When should I plant tomatoes in 50586?

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 50586 get?

About 33.8 inches of precipitation a year and 32 inches of snowfall (NOAA 1991–2020 normals, Rockwell City station).

How hot do summers get in Somers, IA?

The average high peaks at 83 °F in July, with about 13 days a year at 90 °F or more.

What kind of soil does 50586 have?

The USDA soil survey maps Clarion at the center of ZIP 50586: loam, moderately well drained, pH about 6.2 (slightly acidic).

Did spring come early in Somers, IA in 2026?

Spring leaf-out near 50586 came on Mar 25 in 2026, 15 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Somers, IA?

Long-day onions: the longest day near 50586 is 15 h 17 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).