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

Planting zone for 83641 — Melba, ID

ZIP code 83641 (Melba, Canyon County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is May 21 and the first fall frost September 28.

Where ZIP 83641 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 frostMay 21

First frostSep 28

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 Melba, 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 Melba, ID

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 21median — 50% chance of a later frost

Safe for tender plantsJune 12only 10% chance of frost after

First fall frostSeptember 28median — 10% chance by Sep 13

Growing season126 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 5 and returns around October 8.

From the NOAA station Reynolds, ID — 11 miles away, elevation 3,931 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 83641

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 9 – Apr 23

SpinachSow outdoors · Apr 9 – Apr 30

Broccoli, cabbageStart indoors · Mar 12 – Mar 26

Broccoli, cabbageTransplant · Apr 30 – May 14

Onion setsPlant outdoors · Apr 23 – May 7

PotatoesPlant outdoors · Apr 30 – May 14

LettuceSow outdoors · Apr 23 – May 7

Carrots, beetsSow outdoors · Apr 30 – May 14

TomatoesStart indoors · Mar 26 – Apr 9

TomatoesTransplant · May 28 – Jun 11

Peppers, eggplantStart indoors · Mar 12 – Mar 26

Peppers, eggplantTransplant · Jun 4 – Jun 18

BeansSow outdoors · May 28 – Jun 11

Sweet cornSow outdoors · May 28 – Jun 11

Cucumbers, squashSow outdoors · May 28 – Jun 11

Fall lettuce, spinachSow outdoors · Aug 3 – Aug 17

GarlicPlant cloves · Sep 14 – Oct 19

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 21) and first fall frost (Sep 28) 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 83641 came on Mar 5 — 13 days earlier than the 1991–2020 average (Mar 18).

average
Mar 182026
Mar 5

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 Melba, ID.

Soil in Melba, ID

The soil mapped at the center of ZIP 83641 is Garbutt — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH8.4alkaline; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupBwater soaks in moderately

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Garbutt silt loam, 0 to 1 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 83641; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Melba, ID

Summer high87 °Faverage high, July

Winter low20 °Faverage low, December

Hot days32days a year at 90 °F or more

Freezing nights158nights a year at 32 °F or less

Growing degree days2,107base 50 °F — the season’s usable heat

Longest day15 h 24 mindaylight on June 21

Shortest day8 h 58 mindaylight on December 21

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

Precipitation9.9 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: Reynolds, ID (11 mi away); precipitation: Reynolds, ID (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

Idaho planting zones →

Questions about 83641

What planting zone is ZIP code 83641?

ZIP code 83641 (Melba, 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 Melba, ID?

The median last spring frost (32 °F) near 83641 is May 21; after June 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Reynolds station.

When is the first frost in Melba, ID?

The median first fall frost near 83641 is September 28, giving a median frost-free growing season of 126 days.

When should I plant tomatoes in 83641?

Start tomato seeds indoors around Mar 26 – Apr 9 and set transplants outside around May 28 – Jun 11, one to three weeks after the median last frost.

How much rain and snow does 83641 get?

About 9.9 inches of precipitation a year (NOAA 1991–2020 normals, Reynolds station).

How hot do summers get in Melba, ID?

The average high peaks at 87 °F in July, with about 32 days a year at 90 °F or more.

What kind of soil does 83641 have?

The USDA soil survey maps Garbutt at the center of ZIP 83641: silt loam, well drained, pH about 8.4 (alkaline).

Did spring come early in Melba, ID in 2026?

Spring leaf-out near 83641 came on Mar 5 in 2026, 13 days earlier than the 1991–2020 average (Mar 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Melba, ID?

Long-day onions: the longest day near 83641 is 15 h 24 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).