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

Planting zone for 99784 — White Mountain, AK

ZIP code 99784 (White Mountain, Nome (CA) County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is June 5 and the first fall frost September 3.

Where ZIP 99784 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.

Zone4a−30 to −25 °F
Coldest night−34.4 to −31.7 °C
Last frostJun 5
First frostSep 3
2012 zone3a

Was 3a on the 2012 map — a full zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for White Mountain, 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 White Mountain, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 5median — 50% chance of a later frost
Safe for tender plantsJune 26only 10% chance of frost after
First fall frostSeptember 3median — 10% chance by Aug 15
Growing season88 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 23 and returns around September 19.

From the NOAA station Nome Municipal Airport, AK — 61 miles away, elevation 13 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 99784

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 24 – May 8
SpinachSow outdoors · Apr 24 – May 15
Broccoli, cabbageStart indoors · Mar 27 – Apr 10
Broccoli, cabbageTransplant · May 15 – May 29
Onion setsPlant outdoors · May 8 – May 22
PotatoesPlant outdoors · May 15 – May 29
LettuceSow outdoors · May 8 – May 22
Carrots, beetsSow outdoors · May 15 – May 29
TomatoesStart indoors · Apr 10 – Apr 24
TomatoesTransplant · Jun 12 – Jun 26
Peppers, eggplantStart indoors · Mar 27 – Apr 10
Peppers, eggplantTransplant · Jun 19 – Jul 3
BeansSow outdoors · Jun 12 – Jun 26
Sweet cornSow outdoors · Jun 12 – Jun 26
Cucumbers, squashSow outdoors · Jun 12 – Jun 26
Fall lettuce, spinachSow outdoors · Jul 9 – Jul 23
GarlicPlant cloves · Aug 20 – Sep 24
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 5) and first fall frost (Sep 3) 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 4a in Alaska

240 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. Each links to its USDA PLANTS profile.

Trees 10

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 °FSitka spruce200 ft · blooms late spring · low shade tolerance · to −33 °F

Shrubs 42

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 °Fbog Labrador tea3 ft · blooms late spring · medium shade tolerance · to −33 °F

Wildflowers & perennials 102

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 78

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine 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 °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 White Mountain, AK.

Soil in White Mountain, AK

The soil mapped at the center of ZIP 99784 is E40-boreal forest-gravelly till slopes — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer
pH4.0strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter75%high
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Nulato Hills-Southern Seward Peninsula Highlands-Boreal Upland and Maritime Upland-Hills and Plains, Gravelly.

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 99784; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in White Mountain, AK

Summer high58 °Faverage high, July
Winter low−2 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights231nights a year at 32 °F or less
Growing degree days247base 50 °F — the season’s usable heat
Longest day21 h 40 mindaylight on June 21
Shortest day3 h 47 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation15.2 inper year, rain and melted snow

Average high and low, by month

−10°0°10°20°30°40°50°60°70°32 °FJanuary: average high 13 °F, low -2 °F 13°−2° JanFebruary: average high 17 °F, low 1 °F 17°1° FebMarch: average high 18 °F, low 2 °F 18°2° MarApril: average high 29 °F, low 16 °F 29°16° AprMay: average high 44 °F, low 31 °F 44°31° MayJune: average high 55 °F, low 42 °F 55°42° JunJuly: average high 58 °F, low 46 °F 58°46° JulAugust: average high 56 °F, low 44 °F 56°44° AugSeptember: average high 49 °F, low 37 °F 49°37° SepOctober: average high 36 °F, low 25 °F 36°25° OctNovember: average high 24 °F, low 12 °F 24°12° NovDecember: average high 16 °F, low 2 °F 16°2° Dec

Precipitation by month inches

0″1″2″3″4″January: 0.43 in precipitation 0.4 JanFebruary: 0.56 in precipitation 0.6 FebMarch: 0.40 in precipitation 0.4 MarApril: 0.64 in precipitation 0.6 AprMay: 0.67 in precipitation 0.7 MayJune: 0.76 in precipitation 0.8 JunJuly: 2.30 in precipitation 2.3 JulAugust: 3.44 in precipitation 3.4 AugSeptember: 2.34 in precipitation 2.3 SepOctober: 1.86 in precipitation 1.9 OctNovember: 1.03 in precipitation 1.0 NovDecember: 0.77 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Nome Municipal Airport, AK (61 mi away); precipitation: Rocky Point, AK (11 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

5 of the 6 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

997393b
Elim, AK · 26 mi
997623b
Nome, AK · 37 mi
996713b
Stebbins, AK · 90 mi
996593b
Saint Michael, AK · 93 mi
997363a
Deering, AK · 98 mi
996204a
Kotlik, AK · 114 mi

Alaska planting zones →

Questions about 99784

What planting zone is ZIP code 99784?

ZIP code 99784 (White Mountain, AK) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in White Mountain, AK?

The median last spring frost (32 °F) near 99784 is June 5; after June 26 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Nome Municipal Airport station.

When is the first frost in White Mountain, AK?

The median first fall frost near 99784 is September 3, giving a median frost-free growing season of 88 days.

When should I plant tomatoes in 99784?

Start tomato seeds indoors around Apr 10 – Apr 24 and set transplants outside around Jun 12 – Jun 26, one to three weeks after the median last frost.

How much rain and snow does 99784 get?

About 15.2 inches of precipitation a year (NOAA 1991–2020 normals, Rocky Point station).

How hot do summers get in White Mountain, AK?

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

What kind of soil does 99784 have?

The USDA soil survey maps E40-boreal forest-gravelly till slopes at the center of ZIP 99784: slightly decomposed plant material, well drained, pH about 4.0 (strongly acidic).

What kind of onions grow in White Mountain, AK?

Long-day onions: the longest day near 99784 is 21 h 40 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99784 change?

Yes. The 2012 USDA map put 99784 in zone 3a; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.