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

Planting zone for 98851 — Soap Lake, WA

ZIP code 98851 (Soap Lake, Grant County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 22 and the first fall frost October 17.

Where ZIP 98851 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 22
First frostOct 17
2012 zone6b

Was 6b 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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Soap Lake, 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 Soap Lake, WA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 22median — 50% chance of a later frost
Safe for tender plantsMay 6only 10% chance of frost after
First fall frostOctober 17median — 10% chance by Oct 3
Growing season175 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 6 and returns around October 27.

From the NOAA station Ephrata Municipal Airport, WA — 8 miles away, elevation 1,253 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 98851

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 11 – Mar 25
SpinachSow outdoors · Mar 11 – Apr 1
Broccoli, cabbageStart indoors · Feb 11 – Feb 25
Broccoli, cabbageTransplant · Apr 1 – Apr 15
Onion setsPlant outdoors · Mar 25 – Apr 8
PotatoesPlant outdoors · Apr 1 – Apr 15
LettuceSow outdoors · Mar 25 – Apr 8
Carrots, beetsSow outdoors · Apr 1 – Apr 15
TomatoesStart indoors · Feb 25 – Mar 11
TomatoesTransplant · Apr 29 – May 13
Peppers, eggplantStart indoors · Feb 11 – Feb 25
Peppers, eggplantTransplant · May 6 – May 20
BeansSow outdoors · Apr 29 – May 13
Sweet cornSow outdoors · Apr 29 – May 13
Cucumbers, squashSow outdoors · Apr 29 – May 13
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 22) 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 98851 came on Mar 23 — 5 days earlier than the 1991–2020 average (Mar 28).

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 Soap Lake, WA.

Soil in Soap Lake, WA

The soil mapped at the center of ZIP 98851 is Roloff — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH7.2neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter1.5%low — add compost
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Roloff-Bakeoven complex, 5 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 98851; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Soap Lake, WA

Summer high89 °Faverage high, July
Winter low24 °Faverage low, January
Hot days40days a year at 90 °F or more
Freezing nights121nights a year at 32 °F or less
Growing degree days3,010base 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)
Precipitation7.6 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°80°90°100°32 °FJanuary: average high 36 °F, low 24 °F 36°24° JanFebruary: average high 43 °F, low 27 °F 43°27° FebMarch: average high 54 °F, low 32 °F 54°32° MarApril: average high 63 °F, low 39 °F 63°39° AprMay: average high 73 °F, low 48 °F 73°48° MayJune: average high 80 °F, low 54 °F 80°54° JunJuly: average high 89 °F, low 61 °F 89°61° JulAugust: average high 88 °F, low 59 °F 88°59° AugSeptember: average high 79 °F, low 51 °F 79°51° SepOctober: average high 62 °F, low 39 °F 62°39° OctNovember: average high 46 °F, low 30 °F 46°30° NovDecember: average high 36 °F, low 24 °F 36°24° Dec

Precipitation by month inches

0″1″2″January: 0.91 in precipitation 0.9 JanFebruary: 0.64 in precipitation 0.6 FebMarch: 0.70 in precipitation 0.7 MarApril: 0.58 in precipitation 0.6 AprMay: 0.75 in precipitation 0.8 MayJune: 0.65 in precipitation 0.7 JunJuly: 0.30 in precipitation 0.3 JulAugust: 0.18 in precipitation 0.2 AugSeptember: 0.22 in precipitation 0.2 SepOctober: 0.66 in precipitation 0.7 OctNovember: 0.86 in precipitation 0.9 NovDecember: 1.13 in precipitation 1.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Ephrata Municipal Airport, WA (8 mi away); precipitation: Ephrata Municipal Airport, WA (8 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

988536b
Stratford, WA · 8 mi
988236b
Ephrata, WA · 11 mi
988606b
Wilson Creek, WA · 15 mi
991156b
Coulee City, WA · 18 mi
988377a
Moses Lake, WA · 19 mi
988326b
Marlin, WA · 20 mi
991356b
Hartline, WA · 23 mi
988457a
Palisades, WA · 24 mi

Washington planting zones →

Questions about 98851

What planting zone is ZIP code 98851?

ZIP code 98851 (Soap Lake, 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 Soap Lake, WA?

The median last spring frost (32 °F) near 98851 is April 22; after May 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ephrata Municipal Airport station.

When is the first frost in Soap Lake, WA?

The median first fall frost near 98851 is October 17, giving a median frost-free growing season of 175 days.

When should I plant tomatoes in 98851?

Start tomato seeds indoors around Feb 25 – Mar 11 and set transplants outside around Apr 29 – May 13, one to three weeks after the median last frost.

How much rain and snow does 98851 get?

About 7.6 inches of precipitation a year (NOAA 1991–2020 normals, Ephrata Municipal Airport station).

How hot do summers get in Soap Lake, WA?

The average high peaks at 89 °F in July, with about 40 days a year at 90 °F or more.

What kind of soil does 98851 have?

The USDA soil survey maps Roloff at the center of ZIP 98851: silt loam, well drained, pH about 7.2 (neutral).

Did spring come early in Soap Lake, WA in 2026?

Spring leaf-out near 98851 came on Mar 23 in 2026, 5 days earlier than the 1991–2020 average (Mar 28), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Soap Lake, WA?

Long-day onions: the longest day near 98851 is 15 h 57 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 98851 change?

Yes. The 2012 USDA map put 98851 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.