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

Planting zone for 83213 — Arco, ID

ZIP code 83213 (Arco, Butte County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is May 24 and the first fall frost October 1.

Where ZIP 83213 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 frostMay 24

First frostOct 1

2012 zone4b

Was 4b on the 2012 map — half a zone warmer now. 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 Arco, ID…

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 Arco, ID

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 24median — 50% chance of a later frost

Safe for tender plantsJune 15only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 16

Growing season130 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 3 and returns around October 13.

From the NOAA station Arco 17 Sw, ID — 10 miles away, elevation 5,919 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 83213

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 12 – Apr 26

SpinachSow outdoors · Apr 12 – May 3

Broccoli, cabbageStart indoors · Mar 15 – Mar 29

Broccoli, cabbageTransplant · May 3 – May 17

Onion setsPlant outdoors · Apr 26 – May 10

PotatoesPlant outdoors · May 3 – May 17

LettuceSow outdoors · Apr 26 – May 10

Carrots, beetsSow outdoors · May 3 – May 17

TomatoesStart indoors · Mar 29 – Apr 12

TomatoesTransplant · May 31 – Jun 14

Peppers, eggplantStart indoors · Mar 15 – Mar 29

Peppers, eggplantTransplant · Jun 7 – Jun 21

BeansSow outdoors · May 31 – Jun 14

Sweet cornSow outdoors · May 31 – Jun 14

Cucumbers, squashSow outdoors · May 31 – Jun 14

Fall lettuce, spinachSow outdoors · Aug 6 – Aug 20

GarlicPlant cloves · Sep 17 – Oct 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 24) and first fall frost (Oct 1) 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 83213 came on Mar 27 — 26 days earlier than the 1991–2020 average (Apr 22).

average
Apr 222026
Mar 27

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 Idaho

536 plants native to the lower 48 states, recorded in Idaho, 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 Arco, ID.

Soil in Arco, ID

The soil mapped at the center of ZIP 83213 is Huddle — gravelly medial loam, well drained.

TextureGravelly medial loama good balance for most vegetables

pH7.6slightly alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Huddle-Moonville complex, 2 to 12 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 83213; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Arco, ID

Summer high83 °Faverage high, July

Winter low13 °Faverage low, January

Hot days13days a year at 90 °F or more

Freezing nights181nights a year at 32 °F or less

Growing degree days1,916base 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)

Precipitation15.5 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Arco 17 Sw, ID (10 mi away); precipitation: Arco 17 Sw, ID (10 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Springfield, ID · 43 mi

Idaho planting zones →

Questions about 83213

What planting zone is ZIP code 83213?

ZIP code 83213 (Arco, ID) 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 Arco, ID?

The median last spring frost (32 °F) near 83213 is May 24; after June 15 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Arco 17 Sw station.

When is the first frost in Arco, ID?

The median first fall frost near 83213 is October 1, giving a median frost-free growing season of 130 days.

When should I plant tomatoes in 83213?

Start tomato seeds indoors around Mar 29 – Apr 12 and set transplants outside around May 31 – Jun 14, one to three weeks after the median last frost.

How much rain and snow does 83213 get?

About 15.5 inches of precipitation a year (NOAA 1991–2020 normals, Arco 17 Sw station).

How hot do summers get in Arco, ID?

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 83213 have?

The USDA soil survey maps Huddle at the center of ZIP 83213: gravelly medial loam, well drained, pH about 7.6 (slightly alkaline).

Did spring come early in Arco, ID in 2026?

Spring leaf-out near 83213 came on Mar 27 in 2026, 26 days earlier than the 1991–2020 average (Apr 22), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Arco, ID?

Long-day onions: the longest day near 83213 is 15 h 25 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 83213 change?

Yes. The 2012 USDA map put 83213 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.