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

Planting zone for 99031 — Spangle, WA

ZIP code 99031 (Spangle, Spokane County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 30 and the first fall frost September 4.

Where ZIP 99031 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.

Zone6b−5 to 0 °F

Coldest night−20.6 to −17.8 °C

Last frostMay 30

First frostSep 4

2012 zone6a

Was 6a 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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Spangle, WA…

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 Spangle, WA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 30median — 50% chance of a later frost

Safe for tender plantsJuly 13only 10% chance of frost after

First fall frostSeptember 4median — 10% chance by Aug 21

Growing season94 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 5 and returns around September 15.

From the NOAA station Spokane 17 Ssw, WA — 9 miles away, elevation 2,267 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 99031

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 18 – May 2

SpinachSow outdoors · Apr 18 – May 9

Broccoli, cabbageStart indoors · Mar 21 – Apr 4

Broccoli, cabbageTransplant · May 9 – May 23

Onion setsPlant outdoors · May 2 – May 16

PotatoesPlant outdoors · May 9 – May 23

LettuceSow outdoors · May 2 – May 16

Carrots, beetsSow outdoors · May 9 – May 23

TomatoesStart indoors · Apr 4 – Apr 18

TomatoesTransplant · Jun 6 – Jun 20

Peppers, eggplantStart indoors · Mar 21 – Apr 4

Peppers, eggplantTransplant · Jun 13 – Jun 27

BeansSow outdoors · Jun 6 – Jun 20

Sweet cornSow outdoors · Jun 6 – Jun 20

Cucumbers, squashSow outdoors · Jun 6 – Jun 20

Fall lettuce, spinachSow outdoors · Jul 10 – Jul 24

GarlicPlant cloves · Aug 21 – Sep 25

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 30) and first fall frost (Sep 4) 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 99031 came on Apr 2 — 6 days earlier than the 1991–2020 average (Apr 8).

average
Apr 82026
Apr 2

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 6b in Washington

581 plants native to the lower 48 states, recorded in Washington, and rated by the USDA to survive −5 °F or colder — the bottom of zone 6b. 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 Spangle, WA.

Soil in Spangle, WA

The soil mapped at the center of ZIP 99031 is Naff — silt loam, well drained.

TextureSilt loama good balance for most vegetables

pH6.6neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter3%moderate

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Naff-Thatuna complex, 8 to 25 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 99031; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Spangle, WA

Summer high84 °Faverage high, July

Winter low21 °Faverage low, December

Hot days20days a year at 90 °F or more

Freezing nights186nights a year at 32 °F or less

Growing degree days1,420base 50 °F — the season’s usable heat

Longest day15 h 57 mindaylight on June 21

Shortest day8 h 27 mindaylight on December 21

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

Precipitation18.3 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: Spokane 17 Ssw, WA (9 mi away); precipitation: Spokane 17 Ssw, WA (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

Valleyford, WA · 8 mi

Washington planting zones →

Questions about 99031

What planting zone is ZIP code 99031?

ZIP code 99031 (Spangle, WA) is in USDA hardiness zone 6b on the 2023 map: the coldest night of an average winter reaches −5 to 0 °F (−20.6 to −17.8 °C).

When is the last frost in Spangle, WA?

The median last spring frost (32 °F) near 99031 is May 30; after July 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Spokane 17 Ssw station.

When is the first frost in Spangle, WA?

The median first fall frost near 99031 is September 4, giving a median frost-free growing season of 94 days.

When should I plant tomatoes in 99031?

Start tomato seeds indoors around Apr 4 – Apr 18 and set transplants outside around Jun 6 – Jun 20, one to three weeks after the median last frost.

How much rain and snow does 99031 get?

About 18.3 inches of precipitation a year (NOAA 1991–2020 normals, Spokane 17 Ssw station).

How hot do summers get in Spangle, WA?

The average high peaks at 84 °F in July, with about 20 days a year at 90 °F or more.

What kind of soil does 99031 have?

The USDA soil survey maps Naff at the center of ZIP 99031: silt loam, well drained, pH about 6.6 (neutral).

Did spring come early in Spangle, WA in 2026?

Spring leaf-out near 99031 came on Apr 2 in 2026, 6 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Spangle, WA?

Long-day onions: the longest day near 99031 is 15 h 57 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99031 change?

Yes. The 2012 USDA map put 99031 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.