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

Planting zone for 99720 — Allakaket, AK

ZIP code 99720 (Allakaket, Yukon-Koyukuk (CA) County) is in USDA zone 1a: the coldest winter night averages −60 to −55 °F. The median last spring frost is May 22 and the first fall frost August 24.

Where ZIP 99720 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.

Zone1a−60 to −55 °F

Coldest night−51.1 to −48.3 °C

Last frostMay 22

First frostAug 24

2012 zone1b

Was 1b on the 2012 map — half a zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 1a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Allakaket, 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 Allakaket, 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 — 42 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 99720

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 1a in Alaska

37 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −60 °F or colder — the bottom of zone 1a. 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 Allakaket, AK.

Soil in Allakaket, AK

The soil mapped at the center of ZIP 99720 is E31-Boreal taiga-silty frozen loess slopes — peat, poorly drained.

TexturePeattop layer

pH4.8strongly 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: Interior Alaska Highlands-Boreal Upland-Hills and Plains.

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 99720; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Allakaket, AK

Summer high70 °Faverage high, June

Winter low−19 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights239nights a year at 32 °F or less

Growing degree days754base 50 °F — the season’s usable heat

Longest day24 h 00 mindaylight on June 21

Shortest day2 h 10 mindaylight on December 21

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

Precipitation16.6 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: Bettles Airport, AK (42 mi away); precipitation: Bettles Field, AK (42 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

997261b

Bettles Field, AK · 39 mi

Anaktuvuk Pass, AK · 113 mi

Alaska planting zones →

Questions about 99720

What planting zone is ZIP code 99720?

ZIP code 99720 (Allakaket, AK) is in USDA hardiness zone 1a on the 2023 map: the coldest night of an average winter reaches −60 to −55 °F (−51.1 to −48.3 °C).

When is the last frost in Allakaket, AK?

The median last spring frost (32 °F) near 99720 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 Allakaket, AK?

The median first fall frost near 99720 is August 24, giving a median frost-free growing season of 94 days.

When should I plant tomatoes in 99720?

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 99720 get?

About 16.6 inches of precipitation a year (NOAA 1991–2020 normals, Bettles Field station).

How hot do summers get in Allakaket, AK?

The average high peaks at 70 °F in June, with about 0 days a year at 90 °F or more.

What kind of soil does 99720 have?

The USDA soil survey maps E31-Boreal taiga-silty frozen loess slopes at the center of ZIP 99720: peat, poorly drained, pH about 4.8 (strongly acidic).

What kind of onions grow in Allakaket, AK?

Long-day onions: the longest day near 99720 is 24 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99720 change?

Yes. The 2012 USDA map put 99720 in zone 1b; the 2023 map puts it in zone 1a. The newer map uses 1991–2020 data and more weather stations.