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

Planting zone for 98934 — Kittitas, WA

ZIP code 98934 (Kittitas, Kittitas County) is in USDA zone 6b: the coldest winter night averages −5 to 0 °F. The median last spring frost is May 8 and the first fall frost October 2.

Where ZIP 98934 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 8

First frostOct 2

2012 zone6b

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 6b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kittitas, 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 Kittitas, WA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 8median — 50% chance of a later frost

Safe for tender plantsMay 25only 10% chance of frost after

First fall frostOctober 2median — 10% chance by Sep 20

Growing season146 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 23 and returns around October 14.

From the NOAA station Ellensburg, WA — 6 miles away, elevation 1,480 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 98934

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Mar 27 – Apr 10

SpinachSow outdoors · Mar 27 – Apr 17

Broccoli, cabbageStart indoors · Feb 27 – Mar 13

Broccoli, cabbageTransplant · Apr 17 – May 1

Onion setsPlant outdoors · Apr 10 – Apr 24

PotatoesPlant outdoors · Apr 17 – May 1

LettuceSow outdoors · Apr 10 – Apr 24

Carrots, beetsSow outdoors · Apr 17 – May 1

TomatoesStart indoors · Mar 13 – Mar 27

TomatoesTransplant · May 15 – May 29

Peppers, eggplantStart indoors · Feb 27 – Mar 13

Peppers, eggplantTransplant · May 22 – Jun 5

BeansSow outdoors · May 15 – May 29

Sweet cornSow outdoors · May 15 – May 29

Cucumbers, squashSow outdoors · May 15 – May 29

Fall lettuce, spinachSow outdoors · Aug 7 – Aug 21

GarlicPlant cloves · Sep 18 – Oct 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 8) and first fall frost (Oct 2) 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 98934 came on Mar 27 — 5 days earlier than the 1991–2020 average (Apr 1).

average
Apr 12026
Mar 27

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).

Soil in Kittitas, WA

The soil mapped at the center of ZIP 98934 is Opnish — ashy loam, moderately well drained.

TextureAshy loama good balance for most vegetables

pH8.5alkaline; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter3%moderate

Hydrologic groupCwater soaks in slowly

Farmland classPrime farmland if irrigatedUSDA classification

Map unit: Opnish ashy loam, 0 to 2 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 98934; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kittitas, WA

Summer high85 °Faverage high, July

Winter low20 °Faverage low, January

Hot days24days a year at 90 °F or more

Freezing nights155nights a year at 32 °F or less

Growing degree days2,113base 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)

Precipitation9 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, WA (6 mi away); precipitation: Ellensburg, WA (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

989267a

Ellensburg, WA · 3 mi

Washington planting zones →

Questions about 98934

What planting zone is ZIP code 98934?

ZIP code 98934 (Kittitas, 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 Kittitas, WA?

The median last spring frost (32 °F) near 98934 is May 8; after May 25 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ellensburg station.

When is the first frost in Kittitas, WA?

The median first fall frost near 98934 is October 2, giving a median frost-free growing season of 146 days.

When should I plant tomatoes in 98934?

Start tomato seeds indoors around Mar 13 – Mar 27 and set transplants outside around May 15 – May 29, one to three weeks after the median last frost.

How much rain and snow does 98934 get?

About 9 inches of precipitation a year (NOAA 1991–2020 normals, Ellensburg station).

How hot do summers get in Kittitas, WA?

The average high peaks at 85 °F in July, with about 24 days a year at 90 °F or more.

What kind of soil does 98934 have?

The USDA soil survey maps Opnish at the center of ZIP 98934: ashy loam, moderately well drained, pH about 8.5 (alkaline).

Did spring come early in Kittitas, WA in 2026?

Spring leaf-out near 98934 came on Mar 27 in 2026, 5 days earlier than the 1991–2020 average (Apr 1), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Kittitas, WA?

Long-day onions: the longest day near 98934 is 15 h 54 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).