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

Planting zone for 99157 — Northport, WA

ZIP code 99157 (Northport, Stevens 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 1.

Where ZIP 99157 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 1

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 Northport, 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 Northport, 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 26only 10% chance of frost after

First fall frostOctober 1median — 10% chance by Sep 15

Growing season143 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 26 and returns around October 13.

From the NOAA station Northport, WA — 2 miles away, elevation 1,496 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 99157

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 6 – Aug 20

GarlicPlant cloves · Sep 17 – Oct 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 8) and first fall frost (Oct 1) 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 99157 came on Apr 8 — about the same time as the 1991–2020 average (Apr 6).

average
Apr 62026
Apr 8

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 Northport, WA.

Soil in Northport, WA

The soil mapped at the center of ZIP 99157 is Spens — extremely gravelly loamy sand, somewhat excessively drained.

TextureExtremely gravelly loamy sanddrains and warms fast; dries out and needs more feeding

pH6.7neutral; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter1.5%low — add compost

Hydrologic groupAwater soaks in fast

Farmland classNot prime farmlandUSDA classification

Map unit: Spens extremely gravelly loamy sand, 30 to 65 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 99157; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Northport, WA

Summer high86 °Faverage high, August

Winter low21 °Faverage low, January

Hot days33days a year at 90 °F or more

Freezing nights146nights a year at 32 °F or less

Growing degree days1,964base 50 °F — the season’s usable heat

Longest day16 h 11 mindaylight on June 21

Shortest day8 h 14 mindaylight on December 21

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

Precipitation20.3 inper year, rain and melted snow

Snowfall47 inper year; 80 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: Northport, WA (2 mi away); precipitation: Northport, WA (2 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Kettle Falls, WA · 22 mi

Washington planting zones →

Questions about 99157

What planting zone is ZIP code 99157?

ZIP code 99157 (Northport, 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 Northport, WA?

The median last spring frost (32 °F) near 99157 is May 8; after May 26 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Northport station.

When is the first frost in Northport, WA?

The median first fall frost near 99157 is October 1, giving a median frost-free growing season of 143 days.

When should I plant tomatoes in 99157?

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 99157 get?

About 20.3 inches of precipitation a year and 47 inches of snowfall (NOAA 1991–2020 normals, Northport station).

How hot do summers get in Northport, WA?

The average high peaks at 86 °F in August, with about 33 days a year at 90 °F or more.

What kind of soil does 99157 have?

The USDA soil survey maps Spens at the center of ZIP 99157: extremely gravelly loamy sand, somewhat excessively drained, pH about 6.7 (neutral).

Did spring come early in Northport, WA in 2026?

Spring leaf-out near 99157 came on Apr 8 in 2026, about the same as the 1991–2020 average (Apr 6), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Northport, WA?

Long-day onions: the longest day near 99157 is 16 h 11 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).