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

Planting zone for 99113 — Colton, WA

ZIP code 99113 (Colton, Whitman County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 29 and the first fall frost October 2.

Where ZIP 99113 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 29
First frostOct 2
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 Colton, 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 Colton, WA

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostApril 29median — 50% chance of a later frost
Safe for tender plantsMay 14only 10% chance of frost after
First fall frostOctober 2median — 10% chance by Sep 17
Growing season159 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 3 and returns around October 18.

From the NOAA station Pullman Moscow Regional Airport, WA — 12 miles away, elevation 2,553 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 99113

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 18 – Apr 1
SpinachSow outdoors · Mar 18 – Apr 8
Broccoli, cabbageStart indoors · Feb 18 – Mar 4
Broccoli, cabbageTransplant · Apr 8 – Apr 22
Onion setsPlant outdoors · Apr 1 – Apr 15
PotatoesPlant outdoors · Apr 8 – Apr 22
LettuceSow outdoors · Apr 1 – Apr 15
Carrots, beetsSow outdoors · Apr 8 – Apr 22
TomatoesStart indoors · Mar 4 – Mar 18
TomatoesTransplant · May 6 – May 20
Peppers, eggplantStart indoors · Feb 18 – Mar 4
Peppers, eggplantTransplant · May 13 – May 27
BeansSow outdoors · May 6 – May 20
Sweet cornSow outdoors · May 6 – May 20
Cucumbers, squashSow outdoors · May 6 – May 20
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 (Apr 29) 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 99113 came on Mar 18 — 11 days earlier than the 1991–2020 average (Mar 29).

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 Colton, WA.

Soil in Colton, WA

The soil mapped at the center of ZIP 99113 is Palouse — silt loam, well drained.

TextureSilt loama good balance for most vegetables
pH6.5neutral; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter3%moderate
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Palouse silt loam, 25 to 40 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 99113; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Colton, WA

Summer high83 °Faverage high, July
Winter low27 °Faverage low, December
Hot days20days a year at 90 °F or more
Freezing nights119nights a year at 32 °F or less
Growing degree days1,949base 50 °F — the season’s usable heat
Longest day15 h 50 mindaylight on June 21
Shortest day8 h 34 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation17.5 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°80°90°32 °FJanuary: average high 38 °F, low 28 °F 38°28° JanFebruary: average high 42 °F, low 29 °F 42°29° FebMarch: average high 49 °F, low 33 °F 49°33° MarApril: average high 56 °F, low 37 °F 56°37° AprMay: average high 65 °F, low 44 °F 65°44° MayJune: average high 72 °F, low 48 °F 72°48° JunJuly: average high 83 °F, low 51 °F 83°51° JulAugust: average high 83 °F, low 50 °F 83°50° AugSeptember: average high 74 °F, low 45 °F 74°45° SepOctober: average high 59 °F, low 38 °F 59°38° OctNovember: average high 45 °F, low 33 °F 45°33° NovDecember: average high 37 °F, low 27 °F 37°27° Dec

Precipitation by month inches

0″1″2″3″January: 2.15 in precipitation 2.1 JanFebruary: 1.59 in precipitation 1.6 FebMarch: 1.95 in precipitation 1.9 MarApril: 1.79 in precipitation 1.8 AprMay: 1.41 in precipitation 1.4 MayJune: 1.17 in precipitation 1.2 JunJuly: 0.39 in precipitation 0.4 JulAugust: 0.49 in precipitation 0.5 AugSeptember: 0.65 in precipitation 0.7 SepOctober: 1.59 in precipitation 1.6 OctNovember: 2.14 in precipitation 2.1 NovDecember: 2.21 in precipitation 2.2 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Pullman Moscow Regional Airport, WA (12 mi away); precipitation: Pullman Moscow Regional Airport, WA (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

991797a
Uniontown, WA · 7 mi
991636b
Pullman, WA · 10 mi
838446b
Moscow, ID · 13 mi
838327a
Genesee, ID · 14 mi
991027a
Albion, WA · 15 mi
994037b
Clarkston, WA · 15 mi
838436b
Moscow, ID · 15 mi
838726b
Viola, ID · 21 mi

Washington planting zones →

Questions about 99113

What planting zone is ZIP code 99113?

ZIP code 99113 (Colton, 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 Colton, WA?

The median last spring frost (32 °F) near 99113 is April 29; after May 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Pullman Moscow Regional Airport station.

When is the first frost in Colton, WA?

The median first fall frost near 99113 is October 2, giving a median frost-free growing season of 159 days.

When should I plant tomatoes in 99113?

Start tomato seeds indoors around Mar 4 – Mar 18 and set transplants outside around May 6 – May 20, one to three weeks after the median last frost.

How much rain and snow does 99113 get?

About 17.5 inches of precipitation a year (NOAA 1991–2020 normals, Pullman Moscow Regional Airport station).

How hot do summers get in Colton, WA?

The average high peaks at 83 °F in July, with about 20 days a year at 90 °F or more.

What kind of soil does 99113 have?

The USDA soil survey maps Palouse at the center of ZIP 99113: silt loam, well drained, pH about 6.5 (neutral).

Did spring come early in Colton, WA in 2026?

Spring leaf-out near 99113 came on Mar 18 in 2026, 11 days earlier than the 1991–2020 average (Mar 29), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Colton, WA?

Long-day onions: the longest day near 99113 is 15 h 50 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99113 change?

Yes. The 2012 USDA map put 99113 in zone 6b; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.