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

Planting zone for 99134 — Harrington, WA

ZIP code 99134 (Harrington, Lincoln County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 31 and the first fall frost September 12.

Where ZIP 99134 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 31

First frostSep 12

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 Harrington, 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 Harrington, WA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 31median — 50% chance of a later frost

Safe for tender plantsJune 28only 10% chance of frost after

First fall frostSeptember 12median — 10% chance by Aug 23

Growing season101 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 9 and returns around October 1.

From the NOAA station Harrington, WA — 3 miles away, elevation 2,159 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 99134

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 19 – May 3

SpinachSow outdoors · Apr 19 – May 10

Broccoli, cabbageStart indoors · Mar 22 – Apr 5

Broccoli, cabbageTransplant · May 10 – May 24

Onion setsPlant outdoors · May 3 – May 17

PotatoesPlant outdoors · May 10 – May 24

LettuceSow outdoors · May 3 – May 17

Carrots, beetsSow outdoors · May 10 – May 24

TomatoesStart indoors · Apr 5 – Apr 19

TomatoesTransplant · Jun 7 – Jun 21

Peppers, eggplantStart indoors · Mar 22 – Apr 5

Peppers, eggplantTransplant · Jun 14 – Jun 28

BeansSow outdoors · Jun 7 – Jun 21

Sweet cornSow outdoors · Jun 7 – Jun 21

Cucumbers, squashSow outdoors · Jun 7 – Jun 21

Fall lettuce, spinachSow outdoors · Jul 18 – Aug 1

GarlicPlant cloves · Aug 29 – Oct 3

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 31) and first fall frost (Sep 12) 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 99134 came on Mar 23 — 16 days earlier than the 1991–2020 average (Apr 8).

average
Apr 82026
Mar 23

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 Harrington, WA.

Soil in Harrington, WA

The soil mapped at the center of ZIP 99134 is Renslow — 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 groupBwater soaks in moderately

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Renslow silt loam, 0 to 5 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 99134; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Harrington, WA

Summer high85 °Faverage high, July

Winter low22 °Faverage low, December

Hot days21days a year at 90 °F or more

Freezing nights164nights a year at 32 °F or less

Growing degree days1,895base 50 °F — the season’s usable heat

Longest day15 h 58 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)

Precipitation12.6 inper year, rain and melted snow

Snowfall24 inper year; 38 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Harrington, WA (3 mi away); precipitation: Harrington, WA (3 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 6b.

Davenport, WA · 17 mi

Ritzville, WA · 23 mi

991596b

Odessa, WA · 24 mi

Washington planting zones →

Questions about 99134

What planting zone is ZIP code 99134?

ZIP code 99134 (Harrington, 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 Harrington, WA?

The median last spring frost (32 °F) near 99134 is May 31; after June 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Harrington station.

When is the first frost in Harrington, WA?

The median first fall frost near 99134 is September 12, giving a median frost-free growing season of 101 days.

When should I plant tomatoes in 99134?

Start tomato seeds indoors around Apr 5 – Apr 19 and set transplants outside around Jun 7 – Jun 21, one to three weeks after the median last frost.

How much rain and snow does 99134 get?

About 12.6 inches of precipitation a year and 24 inches of snowfall (NOAA 1991–2020 normals, Harrington station).

How hot do summers get in Harrington, WA?

The average high peaks at 85 °F in July, with about 21 days a year at 90 °F or more.

What kind of soil does 99134 have?

The USDA soil survey maps Renslow at the center of ZIP 99134: silt loam, well drained, pH about 7.2 (neutral).

Did spring come early in Harrington, WA in 2026?

Spring leaf-out near 99134 came on Mar 23 in 2026, 16 days earlier than the 1991–2020 average (Apr 8), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Harrington, WA?

Long-day onions: the longest day near 99134 is 15 h 58 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99134 change?

Yes. The 2012 USDA map put 99134 in zone 6a; the 2023 map puts it in zone 6b. The newer map uses 1991–2020 data and more weather stations.