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

Planting zone for 99362 — Walla Walla, WA

ZIP code 99362 (Walla Walla, Walla Walla County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is March 27 and the first fall frost October 31.

Where ZIP 99362 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 frostMar 27
First frostOct 31
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 Walla Walla, 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 Walla Walla, WA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMarch 27median — 50% chance of a later frost
Safe for tender plantsApril 22only 10% chance of frost after
First fall frostOctober 31median — 10% chance by Oct 15
Growing season219 daysfrost-free, median

A hard freeze (28 °F) usually ends around March 4 and returns around November 14.

From the NOAA station Walla Walla Regional Airport, WA — within 1 mile, elevation 1,165 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 99362

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Feb 13 – Feb 27
SpinachSow outdoors · Feb 13 – Mar 6
Broccoli, cabbageStart indoors · Jan 16 – Jan 30
Broccoli, cabbageTransplant · Mar 6 – Mar 20
Onion setsPlant outdoors · Feb 27 – Mar 13
PotatoesPlant outdoors · Mar 6 – Mar 20
LettuceSow outdoors · Feb 27 – Mar 13
Carrots, beetsSow outdoors · Mar 6 – Mar 20
TomatoesStart indoors · Jan 30 – Feb 13
TomatoesTransplant · Apr 3 – Apr 17
Peppers, eggplantStart indoors · Jan 16 – Jan 30
Peppers, eggplantTransplant · Apr 10 – Apr 24
BeansSow outdoors · Apr 3 – Apr 17
Sweet cornSow outdoors · Apr 3 – Apr 17
Cucumbers, squashSow outdoors · Apr 3 – Apr 17
Fall lettuce, spinachSow outdoors · Sep 5 – Sep 19
GarlicPlant cloves · Oct 17 – Nov 21
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Mar 27) and first fall frost (Oct 31) 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 99362 came on Mar 1 — 4 days earlier than the 1991–2020 average (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 Washington

590 plants native to the lower 48 states, recorded in Washington, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. Each links to its USDA PLANTS profile.

Trees 31

Alaska cedar75 ft · blooms mid spring · low shade tolerance · to −22 °FAmerican sycamore100 ft · blooms spring · medium shade tolerance · to −34 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fbigleaf maple60 ft · blooms mid spring · medium shade tolerance · to −14 °Fblack locust60 ft · blooms spring · high shade tolerance · to −37 °Fboxelder60 ft · blooms early spring · low shade tolerance · to −46 °F

Shrubs 105

alderleaf buckthorn3 ft · blooms late spring · low shade tolerance · to −33 °FAllegheny serviceberry35 ft · blooms early spring · low shade tolerance · to −38 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FAmerican plum24 ft · blooms mid spring · high shade tolerance · to −38 °Fantelope bitterbrush6 ft · blooms early spring · medium shade tolerance · to −36 °FBarclay's willow15 ft · high shade tolerance · to −43 °F

Wildflowers & perennials 282

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °FAmerican bistort1.5 ft · blooms mid spring · high shade tolerance · to −38 °FAmerican eelgrass1 ft · blooms mid summer · high shade tolerance · to −33 °F

Grasses 157

Alaska brome5 ft · blooms late spring · low shade tolerance · to −18 °FAlaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °Falkali cordgrass3 ft · blooms late summer · high shade tolerance · to −38 °Falkali sacaton3 ft · blooms mid summer · high shade tolerance · to −38 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °FAmerican beachgrass2.5 ft · blooms spring · high shade tolerance · to −28 °F

Vines 3

riverbank grape45 ft · blooms late spring · medium shade tolerance · to −33 °Ftrumpet creeper2 ft · blooms summer · high shade tolerance · to −13 °Fwestern white clematis1 ft · blooms mid summer · medium shade tolerance · to −38 °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 Walla Walla, WA.

Soil in Walla Walla, WA

The soil mapped at the center of ZIP 99362 is Walla Walla — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH7.0neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter2.5%moderate
Hydrologic groupBwater soaks in moderately
Farmland classprime farmlandUSDA classification

Map unit: Walla Walla silt loam, 0 to 8 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 99362; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Walla Walla, WA

Summer high90 °Faverage high, July
Winter low30 °Faverage low, December
Hot days42days a year at 90 °F or more
Freezing nights70nights a year at 32 °F or less
Growing degree days3,267base 50 °F — the season’s usable heat
Longest day15 h 46 mindaylight on June 21
Shortest day8 h 37 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation18.7 inper year, rain and melted snow
Snowfall7 inper year; 9 days with snow on the ground

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 42 °F, low 31 °F 42°31° JanFebruary: average high 47 °F, low 33 °F 47°33° FebMarch: average high 56 °F, low 38 °F 56°38° MarApril: average high 63 °F, low 43 °F 63°43° AprMay: average high 71 °F, low 49 °F 71°49° MayJune: average high 79 °F, low 55 °F 79°55° JunJuly: average high 90 °F, low 62 °F 90°62° JulAugust: average high 89 °F, low 62 °F 89°62° AugSeptember: average high 79 °F, low 54 °F 79°54° SepOctober: average high 63 °F, low 44 °F 63°44° OctNovember: average high 49 °F, low 36 °F 49°36° NovDecember: average high 41 °F, low 30 °F 41°30° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 2.10 in precipitation, 1 in snowfall 2.1❄1 JanFebruary: 1.59 in precipitation, 2.2 in snowfall 1.6❄2 FebMarch: 2.11 in precipitation, 0.2 in snowfall 2.1 MarApril: 1.98 in precipitation 2.0 AprMay: 2.07 in precipitation 2.1 MayJune: 1.24 in precipitation 1.2 JunJuly: 0.47 in precipitation 0.5 JulAugust: 0.40 in precipitation 0.4 AugSeptember: 0.64 in precipitation 0.6 SepOctober: 1.66 in precipitation, 0.1 in snowfall 1.7 OctNovember: 2.25 in precipitation, 0.3 in snowfall 2.3 NovDecember: 2.23 in precipitation, 2.7 in snowfall 2.2❄3 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Walla Walla Regional Airport, WA (within 1 mile); precipitation: Walla Walla Regional Airport, WA (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 7a.

993247a
College Place, WA · 5 mi
993297a
Dixie, WA · 8 mi
978627a
Milton Freewater, OR · 12 mi
993617a
Waitsburg, WA · 12 mi
993607a
Touchet, WA · 17 mi
978137a
Athena, OR · 20 mi
978867a
Weston, OR · 21 mi
993487a
Prescott, WA · 22 mi

Washington planting zones →

Questions about 99362

What planting zone is ZIP code 99362?

ZIP code 99362 (Walla Walla, WA) 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 Walla Walla, WA?

The median last spring frost (32 °F) near 99362 is March 27; after April 22 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Walla Walla Regional Airport station.

When is the first frost in Walla Walla, WA?

The median first fall frost near 99362 is October 31, giving a median frost-free growing season of 219 days.

When should I plant tomatoes in 99362?

Start tomato seeds indoors around Jan 30 – Feb 13 and set transplants outside around Apr 3 – Apr 17, one to three weeks after the median last frost.

How much rain and snow does 99362 get?

About 18.7 inches of precipitation a year and 7 inches of snowfall (NOAA 1991–2020 normals, Walla Walla Regional Airport station).

How hot do summers get in Walla Walla, WA?

The average high peaks at 90 °F in July, with about 42 days a year at 90 °F or more.

What kind of soil does 99362 have?

The USDA soil survey maps Walla Walla at the center of ZIP 99362: silt loam, well drained, pH about 7.0 (neutral).

Did spring come early in Walla Walla, WA in 2026?

Spring leaf-out near 99362 came on Mar 1 in 2026, 4 days earlier than the 1991–2020 average (Mar 5), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Walla Walla, WA?

Long-day onions: the longest day near 99362 is 15 h 46 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).