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

Planting zone for 99721 — Anaktuvuk Pass, AK

ZIP code 99721 (Anaktuvuk Pass, North Slope County) is in USDA zone 2b: the coldest winter night averages −45 to −40 °F. The median last spring frost is May 22 and the first fall frost August 24.

Where ZIP 99721 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.

Zone2b−45 to −40 °F

Coldest night−42.8 to −40 °C

Last frostMay 22

First frostAug 24

2012 zone2b

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 2b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Anaktuvuk Pass, AK…

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 Anaktuvuk Pass, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 22median — 50% chance of a later frost

Safe for tender plantsJune 5only 10% chance of frost after

First fall frostAugust 24median — 10% chance by Aug 10

Growing season94 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 13 and returns around September 5.

From the NOAA station Bettles Airport, AK — 85 miles away, elevation 643 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 99721

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 10 – Apr 24

SpinachSow outdoors · Apr 10 – May 1

Broccoli, cabbageStart indoors · Mar 13 – Mar 27

Broccoli, cabbageTransplant · May 1 – May 15

Onion setsPlant outdoors · Apr 24 – May 8

PotatoesPlant outdoors · May 1 – May 15

LettuceSow outdoors · Apr 24 – May 8

Carrots, beetsSow outdoors · May 1 – May 15

TomatoesStart indoors · Mar 27 – Apr 10

TomatoesTransplant · May 29 – Jun 12

Peppers, eggplantStart indoors · Mar 13 – Mar 27

Peppers, eggplantTransplant · Jun 5 – Jun 19

BeansSow outdoors · May 29 – Jun 12

Sweet cornSow outdoors · May 29 – Jun 12

Cucumbers, squashSow outdoors · May 29 – Jun 12

Fall lettuce, spinachSow outdoors · Jun 29 – Jul 13

GarlicPlant cloves · Aug 10 – Sep 14

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 22) and first fall frost (Aug 24) 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.

Native plants for zone 2b in Alaska

45 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −45 °F or colder — the bottom of zone 2b. 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 Anaktuvuk Pass, AK.

Soil in Anaktuvuk Pass, AK

The soil mapped at the center of ZIP 99721 is E44-Arctic scrub-sedge-gravelly frozen till slopes — peat, poorly drained.

TexturePeattop layer

pH4.5strongly acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter80%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Northern Brooks Range Mountains-Arctic Upland and Lowland-Glaciated Valleys.

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 99721; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Anaktuvuk Pass, AK

Summer high58 °Faverage high, June

Winter low−11 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights272nights a year at 32 °F or less

Growing degree days201base 50 °F — the season’s usable heat

Longest day24 h 00 mindaylight on June 21

Shortest day0 h 00 mindaylight on December 21

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

Precipitation22.9 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: Chandalar Shelf Dot, AK (55 mi away); precipitation: Atigun Pass, AK (57 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

997261b

Bettles Field, AK · 97 mi

997201a

Allakaket, AK · 113 mi

Alaska planting zones →

Questions about 99721

What planting zone is ZIP code 99721?

ZIP code 99721 (Anaktuvuk Pass, AK) is in USDA hardiness zone 2b on the 2023 map: the coldest night of an average winter reaches −45 to −40 °F (−42.8 to −40 °C).

When is the last frost in Anaktuvuk Pass, AK?

The median last spring frost (32 °F) near 99721 is May 22; after June 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Bettles Airport station.

When is the first frost in Anaktuvuk Pass, AK?

The median first fall frost near 99721 is August 24, giving a median frost-free growing season of 94 days.

When should I plant tomatoes in 99721?

Start tomato seeds indoors around Mar 27 – Apr 10 and set transplants outside around May 29 – Jun 12, one to three weeks after the median last frost.

How much rain and snow does 99721 get?

About 22.9 inches of precipitation a year (NOAA 1991–2020 normals, Atigun Pass station).

How hot do summers get in Anaktuvuk Pass, AK?

The average high peaks at 58 °F in June, with about 0 days a year at 90 °F or more.

What kind of soil does 99721 have?

The USDA soil survey maps E44-Arctic scrub-sedge-gravelly frozen till slopes at the center of ZIP 99721: peat, poorly drained, pH about 4.5 (strongly acidic).

What kind of onions grow in Anaktuvuk Pass, AK?

Long-day onions: the longest day near 99721 is 24 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).