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

Planting zone for 99730 — Central, AK

ZIP code 99730 (Central, Yukon-Koyukuk (CA) County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 25 and the first fall frost August 26.

Where ZIP 99730 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.

Zone3b−35 to −30 °F
Coldest night−37.2 to −34.4 °C
Last frostMay 25
First frostAug 26
2012 zone1b

Was 1b on the 2012 map — 2 zones warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 3b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Central, 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 Central, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 25median — 50% chance of a later frost
Safe for tender plantsJune 6only 10% chance of frost after
First fall frostAugust 26median — 10% chance by Aug 12
Growing season92 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 14 and returns around September 5.

From the NOAA station Central #2, AK — 25 miles away, elevation 919 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 99730

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 13 – Apr 27
SpinachSow outdoors · Apr 13 – May 4
Broccoli, cabbageStart indoors · Mar 16 – Mar 30
Broccoli, cabbageTransplant · May 4 – May 18
Onion setsPlant outdoors · Apr 27 – May 11
PotatoesPlant outdoors · May 4 – May 18
LettuceSow outdoors · Apr 27 – May 11
Carrots, beetsSow outdoors · May 4 – May 18
TomatoesStart indoors · Mar 30 – Apr 13
TomatoesTransplant · Jun 1 – Jun 15
Peppers, eggplantStart indoors · Mar 16 – Mar 30
Peppers, eggplantTransplant · Jun 8 – Jun 22
BeansSow outdoors · Jun 1 – Jun 15
Sweet cornSow outdoors · Jun 1 – Jun 15
Cucumbers, squashSow outdoors · Jun 1 – Jun 15
Fall lettuce, spinachSow outdoors · Jul 1 – Jul 15
GarlicPlant cloves · Aug 12 – Sep 16
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 25) and first fall frost (Aug 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.

Native plants for zone 3b in Alaska

172 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −35 °F or colder — the bottom of zone 3b. Each links to its USDA PLANTS profile.

Trees 8

balsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack spruce65 ft · blooms late spring · low shade tolerance · to −79 °Flodgepole pine99 ft · blooms mid summer · high shade tolerance · to −70 °Fpaper birch70 ft · blooms mid spring · high shade tolerance · to −62 °Fquaking aspen65 ft · blooms mid spring · high shade tolerance · to −70 °Fsubalpine fir90 ft · blooms late spring · low shade tolerance · to −51 °F

Shrubs 32

alpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °FBarclay's willow15 ft · high shade tolerance · to −43 °Fblack crowberry1 ft · blooms mid summer · high shade tolerance · to −43 °Fblack hawthorn15 ft · blooms mid spring · medium shade tolerance · to −47 °Fbog blueberry2 ft · blooms early summer · medium shade tolerance · to −38 °Fchokecherry25 ft · blooms mid spring · high shade tolerance · to −43 °F

Wildflowers & perennials 64

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 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °FAmerican vetch1.3 ft · blooms late spring · high shade tolerance · to −38 °F

Grasses 61

alpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Farctic bluegrass2 ft · high shade tolerance · to −62 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °Fbearded fescue1.2 ft · blooms late spring · low shade tolerance · to −38 °FBebb's sedge3 ft · blooms late spring · low 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 Central, AK.

Soil in Central, AK

The soil mapped at the center of ZIP 99730 is Tatalina — slightly decomposed plant material, poorly drained.

TextureSlightly decomposed plant materialtop layer
DrainagePoorly drainedconsider raised beds
Organic matter75%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Tatalina-Mascot complex, 3 to 18 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 99730; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Central, AK

Summer high73 °Faverage high, July
Winter low−24 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights254nights a year at 32 °F or less
Growing degree days859base 50 °F — the season’s usable heat
Longest day23 h 21 mindaylight on June 21
Shortest day3 h 05 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation18.1 inper year, rain and melted snow

Average high and low, by month

−30°−20°−10°0°10°20°30°40°50°60°70°80°32 °FJanuary: average high -7 °F, low -24 °F −7°−24° JanFebruary: average high 3 °F, low -19 °F 3°−19° FebMarch: average high 17 °F, low -14 °F 17°−14° MarApril: average high 42 °F, low 12 °F 42°12° AprMay: average high 60 °F, low 34 °F 60°34° MayJune: average high 72 °F, low 46 °F 72°46° JunJuly: average high 73 °F, low 49 °F 73°49° JulAugust: average high 66 °F, low 42 °F 66°42° AugSeptember: average high 53 °F, low 30 °F 53°30° SepOctober: average high 29 °F, low 12 °F 29°12° OctNovember: average high 5 °F, low -10 °F 5°−10° NovDecember: average high -1 °F, low -17 °F −1°−17° Dec

Precipitation by month inches

0″1″2″3″4″January: 0.75 in precipitation 0.8 JanFebruary: 0.87 in precipitation 0.9 FebMarch: 0.64 in precipitation 0.6 MarApril: 0.70 in precipitation 0.7 AprMay: 1.27 in precipitation 1.3 MayJune: 2.33 in precipitation 2.3 JunJuly: 3.52 in precipitation 3.5 JulAugust: 3.07 in precipitation 3.1 AugSeptember: 2.16 in precipitation 2.2 SepOctober: 1.23 in precipitation 1.2 OctNovember: 0.89 in precipitation 0.9 NovDecember: 0.68 in precipitation 0.7 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Central #2, AK (25 mi away); precipitation: Eagle Summit, AK (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

997073b
Fairbanks, AK · 39 mi
997331a
Circle, AK · 41 mi
997123b
Fairbanks, AK · 42 mi
997241a
Beaver, AK · 57 mi
997162a
Two Rivers, AK · 65 mi
997022a
Eielson Afb, AK · 80 mi
997143b
Salcha, AK · 92 mi
997063b
Fairbanks, AK · 117 mi

Alaska planting zones →

Questions about 99730

What planting zone is ZIP code 99730?

ZIP code 99730 (Central, AK) is in USDA hardiness zone 3b on the 2023 map: the coldest night of an average winter reaches −35 to −30 °F (−37.2 to −34.4 °C).

When is the last frost in Central, AK?

The median last spring frost (32 °F) near 99730 is May 25; after June 6 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Central #2 station.

When is the first frost in Central, AK?

The median first fall frost near 99730 is August 26, giving a median frost-free growing season of 92 days.

When should I plant tomatoes in 99730?

Start tomato seeds indoors around Mar 30 – Apr 13 and set transplants outside around Jun 1 – Jun 15, one to three weeks after the median last frost.

How much rain and snow does 99730 get?

About 18.1 inches of precipitation a year (NOAA 1991–2020 normals, Eagle Summit station).

How hot do summers get in Central, AK?

The average high peaks at 73 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99730 have?

The USDA soil survey maps Tatalina at the center of ZIP 99730: slightly decomposed plant material, poorly drained.

What kind of onions grow in Central, AK?

Long-day onions: the longest day near 99730 is 23 h 21 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99730 change?

Yes. The 2012 USDA map put 99730 in zone 1b; the 2023 map puts it in zone 3b. The newer map uses 1991–2020 data and more weather stations.