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

Planting zone for 50128 — Jamaica, IA

ZIP code 50128 (Jamaica, Guthrie County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is April 25 and the first fall frost October 10.

Where ZIP 50128 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 25
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 Jamaica, 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 Jamaica, IA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 25median — 50% chance of a later frost
Safe for tender plantsMay 8only 10% chance of frost after
First fall frostOctober 10median — 10% chance by Sep 25
Growing season166 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 16 and returns around October 22.

From the NOAA station Perry, IA — 10 miles away, elevation 951 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 50128

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 14 – Mar 28
SpinachSow outdoors · Mar 14 – Apr 4
Broccoli, cabbageStart indoors · Feb 14 – Feb 28
Broccoli, cabbageTransplant · Apr 4 – Apr 18
Onion setsPlant outdoors · Mar 28 – Apr 11
PotatoesPlant outdoors · Apr 4 – Apr 18
LettuceSow outdoors · Mar 28 – Apr 11
Carrots, beetsSow outdoors · Apr 4 – Apr 18
TomatoesStart indoors · Feb 28 – Mar 14
TomatoesTransplant · May 2 – May 16
Peppers, eggplantStart indoors · Feb 14 – Feb 28
Peppers, eggplantTransplant · May 9 – May 23
BeansSow outdoors · May 2 – May 16
Sweet cornSow outdoors · May 2 – May 16
Cucumbers, squashSow outdoors · May 2 – May 16
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 25) 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 50128 came on Mar 24 — 13 days earlier than the 1991–2020 average (Apr 6).

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 Jamaica, IA.

Soil in Jamaica, IA

The soil mapped at the center of ZIP 50128 is Clarion — loam, well drained.

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

Map unit: Clarion loam, Bemis moraine, 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 50128; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Jamaica, IA

Summer high85 °Faverage high, July
Winter low10 °Faverage low, January
Hot days20days a year at 90 °F or more
Freezing nights151nights a year at 32 °F or less
Growing degree days3,139base 50 °F — the season’s usable heat
Longest day15 h 13 mindaylight on June 21
Shortest day9 h 08 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation34.3 inper year, rain and melted snow
Snowfall33 inper year; 61 days with snow on the ground

Average high and low, by month

0°10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 30 °F, low 10 °F 30°10° JanFebruary: average high 34 °F, low 14 °F 34°14° FebMarch: average high 48 °F, low 26 °F 48°26° MarApril: average high 61 °F, low 37 °F 61°37° AprMay: average high 72 °F, low 49 °F 72°49° MayJune: average high 82 °F, low 60 °F 82°60° JunJuly: average high 85 °F, low 64 °F 85°64° JulAugust: average high 83 °F, low 61 °F 83°61° AugSeptember: average high 77 °F, low 52 °F 77°52° SepOctober: average high 64 °F, low 39 °F 64°39° OctNovember: average high 48 °F, low 27 °F 48°27° NovDecember: average high 35 °F, low 17 °F 35°17° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″5″January: 0.81 in precipitation, 7 in snowfall 0.8❄7 JanFebruary: 1.17 in precipitation, 11.2 in snowfall 1.2❄11 FebMarch: 1.84 in precipitation, 2.6 in snowfall 1.8❄3 MarApril: 3.76 in precipitation, 1 in snowfall 3.8❄1 AprMay: 4.46 in precipitation, 0.3 in snowfall 4.5 MayJune: 4.81 in precipitation 4.8 JunJuly: 4.11 in precipitation 4.1 JulAugust: 3.94 in precipitation 3.9 AugSeptember: 3.57 in precipitation 3.6 SepOctober: 2.86 in precipitation, 0.7 in snowfall 2.9❄1 OctNovember: 1.71 in precipitation, 1.7 in snowfall 1.7❄2 NovDecember: 1.30 in precipitation, 8.3 in snowfall 1.3❄8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Perry, IA (10 mi away); precipitation: Jamaica 3.2 S, IA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

500665a
Dawson, IA · 5 mi
502775a
Yale, IA · 6 mi
502355a
Rippey, IA · 7 mi
500265a
Bagley, IA · 8 mi
502205a
Perry, IA · 9 mi
502165a
Panora, IA · 11 mi
501295b
Jefferson, IA · 12 mi
501465a
Linden, IA · 12 mi

Iowa planting zones →

Questions about 50128

What planting zone is ZIP code 50128?

ZIP code 50128 (Jamaica, 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 Jamaica, IA?

The median last spring frost (32 °F) near 50128 is April 25; after May 8 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Perry station.

When is the first frost in Jamaica, IA?

The median first fall frost near 50128 is October 10, giving a median frost-free growing season of 166 days.

When should I plant tomatoes in 50128?

Start tomato seeds indoors around Feb 28 – Mar 14 and set transplants outside around May 2 – May 16, one to three weeks after the median last frost.

How much rain and snow does 50128 get?

About 34.3 inches of precipitation a year and 33 inches of snowfall (NOAA 1991–2020 normals, Jamaica 3.2 S station).

How hot do summers get in Jamaica, IA?

The average high peaks at 85 °F in July, with about 20 days a year at 90 °F or more.

What kind of soil does 50128 have?

The USDA soil survey maps Clarion at the center of ZIP 50128: loam, well drained, pH about 6.2 (slightly acidic).

Did spring come early in Jamaica, IA in 2026?

Spring leaf-out near 50128 came on Mar 24 in 2026, 13 days earlier than the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Jamaica, IA?

Long-day onions: the longest day near 50128 is 15 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).