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

Planting zone for 99143 — Lacrosse, WA

ZIP code 99143 (Lacrosse, Whitman County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is May 13 and the first fall frost September 26.

Where ZIP 99143 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 frostMay 13

First frostSep 26

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 Lacrosse, 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 Lacrosse, WA

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 13median — 50% chance of a later frost

Safe for tender plantsJune 1only 10% chance of frost after

First fall frostSeptember 26median — 10% chance by Sep 8

Growing season133 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 29 and returns around October 7.

From the NOAA station Lacrosse, WA — 4 miles away, elevation 1,476 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 99143

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 1 – Apr 15

SpinachSow outdoors · Apr 1 – Apr 22

Broccoli, cabbageStart indoors · Mar 4 – Mar 18

Broccoli, cabbageTransplant · Apr 22 – May 6

Onion setsPlant outdoors · Apr 15 – Apr 29

PotatoesPlant outdoors · Apr 22 – May 6

LettuceSow outdoors · Apr 15 – Apr 29

Carrots, beetsSow outdoors · Apr 22 – May 6

TomatoesStart indoors · Mar 18 – Apr 1

TomatoesTransplant · May 20 – Jun 3

Peppers, eggplantStart indoors · Mar 4 – Mar 18

Peppers, eggplantTransplant · May 27 – Jun 10

BeansSow outdoors · May 20 – Jun 3

Sweet cornSow outdoors · May 20 – Jun 3

Cucumbers, squashSow outdoors · May 20 – Jun 3

Fall lettuce, spinachSow outdoors · Aug 1 – Aug 15

GarlicPlant cloves · Sep 12 – Oct 17

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 13) and first fall frost (Sep 26) 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 99143 came on Mar 5 — 13 days earlier than the 1991–2020 average (Mar 18).

average
Mar 182026
Mar 5

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 Lacrosse, WA.

Soil in Lacrosse, WA

The soil mapped at the center of ZIP 99143 is Walla Walla — 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 matter2.5%moderate

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Walla Walla silt loam, 7 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 99143; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lacrosse, WA

Summer high90 °Faverage high, July

Winter low25 °Faverage low, December

Hot days43days a year at 90 °F or more

Freezing nights135nights a year at 32 °F or less

Growing degree days2,423base 50 °F — the season’s usable heat

Longest day15 h 52 mindaylight on June 21

Shortest day8 h 32 mindaylight on December 21

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

Precipitation15.1 inper year, rain and melted snow

Snowfall17 inper year; 21 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: Lacrosse, WA (4 mi away); precipitation: Lacrosse, WA (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Washtucna, WA · 23 mi

991716b

Saint John, WA · 25 mi

Washington planting zones →

Questions about 99143

What planting zone is ZIP code 99143?

ZIP code 99143 (Lacrosse, 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 Lacrosse, WA?

The median last spring frost (32 °F) near 99143 is May 13; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Lacrosse station.

When is the first frost in Lacrosse, WA?

The median first fall frost near 99143 is September 26, giving a median frost-free growing season of 133 days.

When should I plant tomatoes in 99143?

Start tomato seeds indoors around Mar 18 – Apr 1 and set transplants outside around May 20 – Jun 3, one to three weeks after the median last frost.

How much rain and snow does 99143 get?

About 15.1 inches of precipitation a year and 17 inches of snowfall (NOAA 1991–2020 normals, Lacrosse station).

How hot do summers get in Lacrosse, WA?

The average high peaks at 90 °F in July, with about 43 days a year at 90 °F or more.

What kind of soil does 99143 have?

The USDA soil survey maps Walla Walla at the center of ZIP 99143: silt loam, well drained, pH about 7.2 (neutral).

Did spring come early in Lacrosse, WA in 2026?

Spring leaf-out near 99143 came on Mar 5 in 2026, 13 days earlier than the 1991–2020 average (Mar 18), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Lacrosse, WA?

Long-day onions: the longest day near 99143 is 15 h 52 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99143 change?

Yes. The 2012 USDA map put 99143 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.