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

Planting zone for 83604 — Bruneau, ID

ZIP code 83604 (Bruneau, Owyhee County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 17 and the first fall frost October 17.

Where ZIP 83604 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostApr 17

First frostOct 17

2012 zone7a

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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Bruneau, 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 Bruneau, ID

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostApril 17median — 50% chance of a later frost

Safe for tender plantsMay 7only 10% chance of frost after

First fall frostOctober 17median — 10% chance by Oct 1

Growing season181 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 30 and returns around October 31.

From the NOAA station Bruneau, ID — 11 miles away, elevation 2,530 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 83604

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 6 – Mar 20

SpinachSow outdoors · Mar 6 – Mar 27

Broccoli, cabbageStart indoors · Feb 6 – Feb 20

Broccoli, cabbageTransplant · Mar 27 – Apr 10

Onion setsPlant outdoors · Mar 20 – Apr 3

PotatoesPlant outdoors · Mar 27 – Apr 10

LettuceSow outdoors · Mar 20 – Apr 3

Carrots, beetsSow outdoors · Mar 27 – Apr 10

TomatoesStart indoors · Feb 20 – Mar 6

TomatoesTransplant · Apr 24 – May 8

Peppers, eggplantStart indoors · Feb 6 – Feb 20

Peppers, eggplantTransplant · May 1 – May 15

BeansSow outdoors · Apr 24 – May 8

Sweet cornSow outdoors · Apr 24 – May 8

Cucumbers, squashSow outdoors · Apr 24 – May 8

Fall lettuce, spinachSow outdoors · Aug 22 – Sep 5

GarlicPlant cloves · Oct 3 – Nov 7

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 17) and first fall frost (Oct 17) 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 83604 came on Mar 10 — 13 days earlier than the 1991–2020 average (Mar 23).

average
Mar 232026
Mar 10

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 7a in Idaho

575 plants native to the lower 48 states, recorded in Idaho, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 Bruneau, ID.

Soil in Bruneau, ID

The soil mapped at the center of ZIP 83604 is Xeric Torriorthents — fine sandy loam, well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Xeric Torriorthents and Xerollic Camborthids, 8 to 20 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 83604; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Bruneau, ID

Summer high96 °Faverage high, July

Winter low26 °Faverage low, December

Hot days63days a year at 90 °F or more

Freezing nights121nights a year at 32 °F or less

Growing degree days3,580base 50 °F — the season’s usable heat

Longest day15 h 20 mindaylight on June 21

Shortest day9 h 02 mindaylight on December 21

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

Precipitation7.4 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: Bruneau, ID (11 mi away); precipitation: Bruneau, ID (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

836277a

Hammett, ID · 14 mi

836487a

Mountain Home Afb, ID · 23 mi

836237a

Glenns Ferry, ID · 25 mi

836247a

Grand View, ID · 27 mi

836337a

King Hill, ID · 32 mi

Idaho planting zones →

Questions about 83604

What planting zone is ZIP code 83604?

ZIP code 83604 (Bruneau, ID) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Bruneau, ID?

The median last spring frost (32 °F) near 83604 is April 17; after May 7 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Bruneau station.

When is the first frost in Bruneau, ID?

The median first fall frost near 83604 is October 17, giving a median frost-free growing season of 181 days.

When should I plant tomatoes in 83604?

Start tomato seeds indoors around Feb 20 – Mar 6 and set transplants outside around Apr 24 – May 8, one to three weeks after the median last frost.

How much rain and snow does 83604 get?

About 7.4 inches of precipitation a year (NOAA 1991–2020 normals, Bruneau station).

How hot do summers get in Bruneau, ID?

The average high peaks at 96 °F in July, with about 63 days a year at 90 °F or more.

What kind of soil does 83604 have?

The USDA soil survey maps Xeric Torriorthents at the center of ZIP 83604: fine sandy loam, well drained, pH about 8.2 (alkaline).

Did spring come early in Bruneau, ID in 2026?

Spring leaf-out near 83604 came on Mar 10 in 2026, 13 days earlier than the 1991–2020 average (Mar 23), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Bruneau, ID?

Long-day onions: the longest day near 83604 is 15 h 20 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).