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

Planting zone for 98946 — Thorp, WA

ZIP code 98946 (Thorp, Kittitas 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 7.

Where ZIP 98946 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 7

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 Thorp, 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 Thorp, 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 12only 10% chance of frost after

First fall frostOctober 7median — 10% chance by Sep 26

Growing season163 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around October 20.

From the NOAA station Ellensburg Bowers Field, WA — 11 miles away, elevation 1,765 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 98946

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 12 – Aug 26

GarlicPlant cloves · Sep 23 – Oct 28

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 28) and first fall frost (Oct 7) 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 98946 came on Apr 2 — 7 days earlier than the 1991–2020 average (Apr 9).

average
Apr 92026
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 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.

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 Thorp, WA.

Soil in Thorp, WA

The soil mapped at the center of ZIP 98946 is Laufer — very cobbly loam, well drained.

TextureVery cobbly loama good balance for most vegetables

pH7.0neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2.5%moderate

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Laufer-Thiessen-Rubble land complex, 30 to 75 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 98946; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Thorp, WA

Summer high87 °Faverage high, August

Winter low24 °Faverage low, January

Hot days34days a year at 90 °F or more

Freezing nights139nights a year at 32 °F or less

Growing degree days2,532base 50 °F — the season’s usable heat

Longest day15 h 54 mindaylight on June 21

Shortest day8 h 30 mindaylight on December 21

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

Precipitation10.8 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: Ellensburg Bowers Field, WA (11 mi away); precipitation: Ellensburg #2, WA (11 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.

989227a

Cle Elum, WA · 12 mi

989437a

South Cle Elum, WA · 13 mi

Ellensburg, WA · 20 mi

989407a

Ronald, WA · 24 mi

988477a

Peshastin, WA · 25 mi

Washington planting zones →

Questions about 98946

What planting zone is ZIP code 98946?

ZIP code 98946 (Thorp, 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 Thorp, WA?

The median last spring frost (32 °F) near 98946 is April 28; after May 12 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ellensburg Bowers Field station.

When is the first frost in Thorp, WA?

The median first fall frost near 98946 is October 7, giving a median frost-free growing season of 163 days.

When should I plant tomatoes in 98946?

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 98946 get?

About 10.8 inches of precipitation a year (NOAA 1991–2020 normals, Ellensburg #2 station).

How hot do summers get in Thorp, WA?

The average high peaks at 87 °F in August, with about 34 days a year at 90 °F or more.

What kind of soil does 98946 have?

The USDA soil survey maps Laufer at the center of ZIP 98946: very cobbly loam, well drained, pH about 7.0 (neutral).

Did spring come early in Thorp, WA in 2026?

Spring leaf-out near 98946 came on Apr 2 in 2026, 7 days earlier than the 1991–2020 average (Apr 9), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Thorp, WA?

Long-day onions: the longest day near 98946 is 15 h 54 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 98946 change?

Yes. The 2012 USDA map put 98946 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.