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

Planting zone for 99790 — Fairbanks, AK

ZIP code 99790 (Fairbanks, Fairbanks North Star County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 28 and the first fall frost August 26.

Where ZIP 99790 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 28
First frostAug 26
2012 zone2a

Was 2a on the 2012 map — 1.5 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 Fairbanks, 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 Fairbanks, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 28median — 50% chance of a later frost
Safe for tender plantsJune 19only 10% chance of frost after
First fall frostAugust 26median — 10% chance by Aug 9
Growing season87 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 14 and returns around September 6.

From the NOAA station Mile 42 Steese, AK — 32 miles away, elevation 961 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 99790

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 16 – Apr 30
SpinachSow outdoors · Apr 16 – May 7
Broccoli, cabbageStart indoors · Mar 19 – Apr 2
Broccoli, cabbageTransplant · May 7 – May 21
Onion setsPlant outdoors · Apr 30 – May 14
PotatoesPlant outdoors · May 7 – May 21
LettuceSow outdoors · Apr 30 – May 14
Carrots, beetsSow outdoors · May 7 – May 21
TomatoesStart indoors · Apr 2 – Apr 16
TomatoesTransplant · Jun 4 – Jun 18
Peppers, eggplantStart indoors · Mar 19 – Apr 2
Peppers, eggplantTransplant · Jun 11 – Jun 25
BeansSow outdoors · Jun 4 – Jun 18
Sweet cornSow outdoors · Jun 4 – Jun 18
Cucumbers, squashSow outdoors · Jun 4 – Jun 18
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 28) 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 Fairbanks, AK.

Soil in Fairbanks, AK

The soil mapped at the center of ZIP 99790 is Mascot — moderately decomposed plant material, well drained.

TextureModerately decomposed plant materialtop layer
DrainageWell drainednatural drainage class
Organic matter75%high
Hydrologic groupCwater soaks in slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Mascot-Tatalina complex, 3 to 20 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 99790; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Fairbanks, AK

Summer high70 °Faverage high, July
Winter low−11 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights247nights a year at 32 °F or less
Growing degree days662base 50 °F — the season’s usable heat
Longest day22 h 48 mindaylight on June 21
Shortest day3 h 14 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation15.4 inper year, rain and melted snow

Average high and low, by month

−20°−10°0°10°20°30°40°50°60°70°80°32 °FJanuary: average high 6 °F, low -11 °F 6°−11° JanFebruary: average high 14 °F, low -5 °F 14°−5° FebMarch: average high 24 °F, low -1 °F 24°−1° MarApril: average high 43 °F, low 19 °F 43°19° AprMay: average high 58 °F, low 34 °F 58°34° MayJune: average high 69 °F, low 44 °F 69°44° JunJuly: average high 70 °F, low 47 °F 70°47° JulAugust: average high 64 °F, low 41 °F 64°41° AugSeptember: average high 53 °F, low 31 °F 53°31° SepOctober: average high 34 °F, low 15 °F 34°15° OctNovember: average high 14 °F, low -2 °F 14°−2° NovDecember: average high 8 °F, low -7 °F 8°−7° Dec

Precipitation by month inches

0″1″2″3″4″January: 0.57 in precipitation 0.6 JanFebruary: 0.61 in precipitation 0.6 FebMarch: 0.40 in precipitation 0.4 MarApril: 0.32 in precipitation 0.3 AprMay: 0.94 in precipitation 0.9 MayJune: 2.13 in precipitation 2.1 JunJuly: 3.03 in precipitation 3.0 JulAugust: 3.25 in precipitation 3.3 AugSeptember: 1.68 in precipitation 1.7 SepOctober: 0.90 in precipitation 0.9 OctNovember: 1.05 in precipitation 1.1 NovDecember: 0.53 in precipitation 0.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Mile 42 Steese, AK (32 mi away); precipitation: Mile 42 Steese, AK (32 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

997082a
Fairbanks, AK · 36 mi
997093b
Fairbanks, AK · 40 mi
997253b
Ester, AK · 41 mi
997752b
Fairbanks, AK · 42 mi
997102b
Fairbanks, AK · 44 mi
997112a
Fairbanks, AK · 44 mi
997032a
Fort Wainwright, AK · 45 mi
997741a
Stevens Village, AK · 48 mi

All 10 ZIP codes in Fairbanks → · Alaska planting zones →

Questions about 99790

What planting zone is ZIP code 99790?

ZIP code 99790 (Fairbanks, 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 Fairbanks, AK?

The median last spring frost (32 °F) near 99790 is May 28; after June 19 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mile 42 Steese station.

When is the first frost in Fairbanks, AK?

The median first fall frost near 99790 is August 26, giving a median frost-free growing season of 87 days.

When should I plant tomatoes in 99790?

Start tomato seeds indoors around Apr 2 – Apr 16 and set transplants outside around Jun 4 – Jun 18, one to three weeks after the median last frost.

How much rain and snow does 99790 get?

About 15.4 inches of precipitation a year (NOAA 1991–2020 normals, Mile 42 Steese station).

How hot do summers get in Fairbanks, AK?

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

What kind of soil does 99790 have?

The USDA soil survey maps Mascot at the center of ZIP 99790: moderately decomposed plant material, well drained.

What kind of onions grow in Fairbanks, AK?

Long-day onions: the longest day near 99790 is 22 h 48 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99790 change?

Yes. The 2012 USDA map put 99790 in zone 2a; the 2023 map puts it in zone 3b. The newer map uses 1991–2020 data and more weather stations.