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

Planting zone for 99348 — Prescott, WA

ZIP code 99348 (Prescott, Walla Walla County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 28 and the first fall frost October 13.

Where ZIP 99348 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 28
First frostOct 13
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 Prescott, 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 Prescott, WA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 28median — 50% chance of a later frost
Safe for tender plantsMay 14only 10% chance of frost after
First fall frostOctober 13median — 10% chance by Sep 30
Growing season168 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around October 25.

From the NOAA station Dayton 1 Wsw, WA — 22 miles away, elevation 1,558 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 99348

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 17 – Mar 31
SpinachSow outdoors · Mar 17 – Apr 7
Broccoli, cabbageStart indoors · Feb 17 – Mar 3
Broccoli, cabbageTransplant · Apr 7 – Apr 21
Onion setsPlant outdoors · Mar 31 – Apr 14
PotatoesPlant outdoors · Apr 7 – Apr 21
LettuceSow outdoors · Mar 31 – Apr 14
Carrots, beetsSow outdoors · Apr 7 – Apr 21
TomatoesStart indoors · Mar 3 – Mar 17
TomatoesTransplant · May 5 – May 19
Peppers, eggplantStart indoors · Feb 17 – Mar 3
Peppers, eggplantTransplant · May 12 – May 26
BeansSow outdoors · May 5 – May 19
Sweet cornSow outdoors · May 5 – May 19
Cucumbers, squashSow outdoors · May 5 – May 19
Fall lettuce, spinachSow outdoors · Aug 18 – Sep 1
GarlicPlant cloves · Sep 29 – Nov 3
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 13) 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 99348 came on Mar 5 — 7 days earlier than the 1991–2020 average (Mar 12).

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 Prescott, WA.

Soil in Prescott, WA

The soil mapped at the center of ZIP 99348 is Ritzville — 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 matter1.5%low — add compost
Hydrologic groupBwater soaks in moderately
Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Ritzville 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 99348; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Prescott, WA

Summer high88 °Faverage high, July
Winter low26 °Faverage low, January
Hot days31days a year at 90 °F or more
Freezing nights113nights a year at 32 °F or less
Growing degree days2,541base 50 °F — the season’s usable heat
Longest day15 h 49 mindaylight on June 21
Shortest day8 h 35 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation10.3 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 42 °F, low 26 °F 42°26° JanFebruary: average high 46 °F, low 28 °F 46°28° FebMarch: average high 54 °F, low 33 °F 54°33° MarApril: average high 61 °F, low 38 °F 61°38° AprMay: average high 70 °F, low 45 °F 70°45° MayJune: average high 77 °F, low 50 °F 77°50° JunJuly: average high 88 °F, low 55 °F 88°55° JulAugust: average high 87 °F, low 54 °F 87°54° AugSeptember: average high 77 °F, low 47 °F 77°47° SepOctober: average high 63 °F, low 38 °F 63°38° OctNovember: average high 49 °F, low 31 °F 49°31° NovDecember: average high 41 °F, low 27 °F 41°27° Dec

Precipitation by month inches

0″1″2″January: 1.34 in precipitation 1.3 JanFebruary: 0.87 in precipitation 0.9 FebMarch: 1.06 in precipitation 1.1 MarApril: 0.81 in precipitation 0.8 AprMay: 0.90 in precipitation 0.9 MayJune: 0.63 in precipitation 0.6 JunJuly: 0.28 in precipitation 0.3 JulAugust: 0.21 in precipitation 0.2 AugSeptember: 0.40 in precipitation 0.4 SepOctober: 0.89 in precipitation 0.9 OctNovember: 1.38 in precipitation 1.4 NovDecember: 1.57 in precipitation 1.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Dayton 1 Wsw, WA (22 mi away); precipitation: Connell 12 Se, WA (18 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

993597b
Starbuck, WA · 15 mi
993357a
Kahlotus, WA · 17 mi
993617a
Waitsburg, WA · 18 mi
993627a
Walla Walla, WA · 22 mi
993297a
Dixie, WA · 23 mi
993607a
Touchet, WA · 24 mi
993017a
Pasco, WA · 25 mi
993337a
Hooper, WA · 25 mi

Washington planting zones →

Questions about 99348

What planting zone is ZIP code 99348?

ZIP code 99348 (Prescott, 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 Prescott, WA?

The median last spring frost (32 °F) near 99348 is April 28; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Dayton 1 Wsw station.

When is the first frost in Prescott, WA?

The median first fall frost near 99348 is October 13, giving a median frost-free growing season of 168 days.

When should I plant tomatoes in 99348?

Start tomato seeds indoors around Mar 3 – Mar 17 and set transplants outside around May 5 – May 19, one to three weeks after the median last frost.

How much rain and snow does 99348 get?

About 10.3 inches of precipitation a year (NOAA 1991–2020 normals, Connell 12 Se station).

How hot do summers get in Prescott, WA?

The average high peaks at 88 °F in July, with about 31 days a year at 90 °F or more.

What kind of soil does 99348 have?

The USDA soil survey maps Ritzville at the center of ZIP 99348: silt loam, well drained, pH about 7.0 (neutral).

Did spring come early in Prescott, WA in 2026?

Spring leaf-out near 99348 came on Mar 5 in 2026, 7 days earlier than the 1991–2020 average (Mar 12), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Prescott, WA?

Long-day onions: the longest day near 99348 is 15 h 49 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).