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

Planting zone for 99703 — Fort Wainwright, AK

ZIP code 99703 (Fort Wainwright, Fairbanks North Star County) is in USDA zone 2a: the coldest winter night averages −50 to −45 °F. The median last spring frost is May 16 and the first fall frost September 6.

Where ZIP 99703 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.

Zone2a−50 to −45 °F
Coldest night−45.6 to −42.8 °C
Last frostMay 16
First frostSep 6
2012 zone2a

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 2a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Fort Wainwright, 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 Fort Wainwright, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 16median — 50% chance of a later frost
Safe for tender plantsMay 29only 10% chance of frost after
First fall frostSeptember 6median — 10% chance by Aug 25
Growing season112 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 7 and returns around September 18.

From the NOAA station Aurora, AK — 3 miles away, elevation 443 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 99703

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 4 – Apr 18
SpinachSow outdoors · Apr 4 – Apr 25
Broccoli, cabbageStart indoors · Mar 7 – Mar 21
Broccoli, cabbageTransplant · Apr 25 – May 9
Onion setsPlant outdoors · Apr 18 – May 2
PotatoesPlant outdoors · Apr 25 – May 9
LettuceSow outdoors · Apr 18 – May 2
Carrots, beetsSow outdoors · Apr 25 – May 9
TomatoesStart indoors · Mar 21 – Apr 4
TomatoesTransplant · May 23 – Jun 6
Peppers, eggplantStart indoors · Mar 7 – Mar 21
Peppers, eggplantTransplant · May 30 – Jun 13
BeansSow outdoors · May 23 – Jun 6
Sweet cornSow outdoors · May 23 – Jun 6
Cucumbers, squashSow outdoors · May 23 – Jun 6
Fall lettuce, spinachSow outdoors · Jul 12 – Jul 26
GarlicPlant cloves · Aug 23 – Sep 27
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 16) and first fall frost (Sep 6) 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 2a in Alaska

44 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −50 °F or colder — the bottom of zone 2a. 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 16

alpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °Fhalberd willow3 ft · blooms early summer · to −62 °FLapland rosebay3 ft · blooms late spring · low shade tolerance · to −62 °Flingonberry0.5 ft · blooms summer · high shade tolerance · to −62 °FMacKenzie's willow45 ft · blooms early spring · high shade tolerance · to −50 °Fmarsh Labrador tea0.5 ft · blooms summer · to −62 °F

Wildflowers & perennials 12

alpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °Farctic dock1 ft · blooms summer · high shade tolerance · to −62 °Farctic lupine2 ft · blooms spring · medium shade tolerance · to −62 °Farctic poppy1.5 ft · blooms summer · low shade tolerance · to −54 °Farctic raspberry1 ft · blooms summer · high shade tolerance · to −62 °Feightpetal mountain-avens0.3 ft · blooms late spring · medium shade tolerance · to −62 °F

Grasses 6

arctic bluegrass2 ft · high shade tolerance · to −62 °FHoppner's sedge1 ft · high shade tolerance · to −52 °Flargeflower speargrass2 ft · high shade tolerance · to −52 °Flivid sedge1 ft · blooms early summer · high shade tolerance · to −62 °FLyngbye's sedge1 ft · high shade tolerance · to −52 °FRamensk's sedge1 ft · high shade tolerance · to −52 °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 Fort Wainwright, AK.

Soil in Fort Wainwright, AK

The center of ZIP 99703 is mapped as Urban land: built-over ground without natural soil data. Garden soil here is usually imported or disturbed — test before you plant.

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 99703; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fort Wainwright, AK

Summer high73 °Faverage high, July
Winter low−15 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights227nights a year at 32 °F or less
Growing degree days1,010base 50 °F — the season’s usable heat
Longest day21 h 50 mindaylight on June 21
Shortest day3 h 41 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation13 inper year, rain and melted snow
Snowfall58 inper year; 186 days with snow on the ground

Average high and low, by month

−30°−20°−10°0°10°20°30°40°50°60°70°80°32 °FJanuary: average high 0 °F, low -15 °F 0°−15° JanFebruary: average high 13 °F, low -9 °F 13°−9° FebMarch: average high 27 °F, low 0 °F 27°0° MarApril: average high 47 °F, low 21 °F 47°21° AprMay: average high 63 °F, low 37 °F 63°37° MayJune: average high 72 °F, low 49 °F 72°49° JunJuly: average high 73 °F, low 52 °F 73°52° JulAugust: average high 66 °F, low 46 °F 66°46° AugSeptember: average high 55 °F, low 35 °F 55°35° SepOctober: average high 34 °F, low 18 °F 34°18° OctNovember: average high 12 °F, low -3 °F 12°−3° NovDecember: average high 3 °F, low -11 °F 3°−11° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″January: 0.57 in precipitation, 8.7 in snowfall 0.6❄9 JanFebruary: 0.44 in precipitation, 9.6 in snowfall 0.4❄10 FebMarch: 0.34 in precipitation, 6.1 in snowfall 0.3❄6 MarApril: 0.34 in precipitation, 2.8 in snowfall 0.3❄3 AprMay: 0.64 in precipitation, 0.2 in snowfall 0.6 MayJune: 2.01 in precipitation 2.0 JunJuly: 2.62 in precipitation 2.6 JulAugust: 2.44 in precipitation 2.4 AugSeptember: 1.59 in precipitation, 1.3 in snowfall 1.6❄1 SepOctober: 0.77 in precipitation, 5.4 in snowfall 0.8❄5 OctNovember: 0.72 in precipitation, 13.2 in snowfall 0.7❄13 NovDecember: 0.53 in precipitation, 10.5 in snowfall 0.5❄11 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Aurora, AK (3 mi away); precipitation: Aurora, AK (3 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.

997102b
Fairbanks, AK · 3 mi
997112a
Fairbanks, AK · 3 mi
997752b
Fairbanks, AK · 6 mi
997082a
Fairbanks, AK · 10 mi
997052a
North Pole, AK · 11 mi
997253b
Ester, AK · 12 mi
997093b
Fairbanks, AK · 16 mi
997022a
Eielson Afb, AK · 21 mi

Alaska planting zones →

Questions about 99703

What planting zone is ZIP code 99703?

ZIP code 99703 (Fort Wainwright, AK) is in USDA hardiness zone 2a on the 2023 map: the coldest night of an average winter reaches −50 to −45 °F (−45.6 to −42.8 °C).

When is the last frost in Fort Wainwright, AK?

The median last spring frost (32 °F) near 99703 is May 16; after May 29 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Aurora station.

When is the first frost in Fort Wainwright, AK?

The median first fall frost near 99703 is September 6, giving a median frost-free growing season of 112 days.

When should I plant tomatoes in 99703?

Start tomato seeds indoors around Mar 21 – Apr 4 and set transplants outside around May 23 – Jun 6, one to three weeks after the median last frost.

How much rain and snow does 99703 get?

About 13 inches of precipitation a year and 58 inches of snowfall (NOAA 1991–2020 normals, Aurora station).

How hot do summers get in Fort Wainwright, AK?

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

What kind of onions grow in Fort Wainwright, AK?

Long-day onions: the longest day near 99703 is 21 h 50 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).