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

Planting zone for 99801 — Juneau, AK

ZIP code 99801 (Juneau, Juneau City and Borough) is in USDA zone 6a: the coldest winter night averages −10 to −5 °F. The median last spring frost is May 3 and the first fall frost October 14.

Where ZIP 99801 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.

Zone6a−10 to −5 °F
Coldest night−23.3 to −20.6 °C
Last frostMay 3
First frostOct 14
2012 zone6b

Was 6b 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 6a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Juneau, 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 Juneau, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 3median — 50% chance of a later frost
Safe for tender plantsMay 18only 10% chance of frost after
First fall frostOctober 14median — 10% chance by Oct 1
Growing season164 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 11 and returns around October 31.

From the NOAA station Annex Creek, AK — 5 miles away, elevation 92 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 99801

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 22 – Apr 5
SpinachSow outdoors · Mar 22 – Apr 12
Broccoli, cabbageStart indoors · Feb 22 – Mar 8
Broccoli, cabbageTransplant · Apr 12 – Apr 26
Onion setsPlant outdoors · Apr 5 – Apr 19
PotatoesPlant outdoors · Apr 12 – Apr 26
LettuceSow outdoors · Apr 5 – Apr 19
Carrots, beetsSow outdoors · Apr 12 – Apr 26
TomatoesStart indoors · Mar 8 – Mar 22
TomatoesTransplant · May 10 – May 24
Peppers, eggplantStart indoors · Feb 22 – Mar 8
Peppers, eggplantTransplant · May 17 – May 31
BeansSow outdoors · May 10 – May 24
Sweet cornSow outdoors · May 10 – May 24
Cucumbers, squashSow outdoors · May 10 – May 24
Fall lettuce, spinachSow outdoors · Aug 19 – Sep 2
GarlicPlant cloves · Sep 30 – Nov 4
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 3) and first fall frost (Oct 14) 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 6a in Alaska

285 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −10 °F or colder — the bottom of zone 6a. Each links to its USDA PLANTS profile.

Trees 16

Alaska cedar75 ft · blooms mid spring · low shade tolerance · to −22 °Fbalsam 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 °Fmountain hemlock125 ft · blooms early summer · low shade tolerance · to −18 °FPacific silver fir165 ft · blooms late spring · low shade tolerance · to −28 °F

Shrubs 49

alpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °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 °F

Wildflowers & perennials 123

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine aster0.3 ft · blooms early summer · medium shade tolerance · to −28 °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 alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °F

Grasses 88

Alaska brome5 ft · blooms late spring · low shade tolerance · to −18 °FAlaska 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 °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 Juneau, AK.

Soil in Juneau, AK

The soil mapped at the center of ZIP 99801 is Typic Humicryepts — moderately decomposed plant material, moderately well drained.

TextureModerately decomposed plant materialtop layer
pH3.9strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter80%high
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Typic Humicryept and Lithic Cryorthent soils, 76 to 140 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 99801; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Juneau, AK

Summer high59 °Faverage high, June
Winter low20 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights149nights a year at 32 °F or less
Growing degree days293base 50 °F — the season’s usable heat
Longest day18 h 18 mindaylight on June 21
Shortest day6 h 21 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation88.5 inper year, rain and melted snow

Average high and low, by month

10°20°30°40°50°60°70°32 °FJanuary: average high 29 °F, low 20 °F 29°20° JanFebruary: average high 32 °F, low 23 °F 32°23° FebMarch: average high 37 °F, low 27 °F 37°27° MarApril: average high 46 °F, low 33 °F 46°33° AprMay: average high 54 °F, low 39 °F 54°39° MayJune: average high 59 °F, low 45 °F 59°45° JunJuly: average high 59 °F, low 46 °F 59°46° JulAugust: average high 59 °F, low 45 °F 59°45° AugSeptember: average high 53 °F, low 43 °F 53°43° SepOctober: average high 45 °F, low 37 °F 45°37° OctNovember: average high 35 °F, low 28 °F 35°28° NovDecember: average high 29 °F, low 22 °F 29°22° Dec

Precipitation by month inches

0″2″4″6″8″10″12″January: 8.20 in precipitation 8.2 JanFebruary: 5.05 in precipitation 5.0 FebMarch: 5.15 in precipitation 5.2 MarApril: 5.23 in precipitation 5.2 AprMay: 4.86 in precipitation 4.9 MayJune: 5.23 in precipitation 5.2 JunJuly: 7.68 in precipitation 7.7 JulAugust: 8.48 in precipitation 8.5 AugSeptember: 11.57 in precipitation 11.6 SepOctober: 10.13 in precipitation 10.1 OctNovember: 8.84 in precipitation 8.8 NovDecember: 8.12 in precipitation 8.1 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Annex Creek, AK (5 mi away); precipitation: Juneau-Douglas Wwtp, AK (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

998027a
Juneau, AK · 10 mi
998037a
Juneau, AK · 10 mi
998117a
Juneau, AK · 10 mi
998247a
Douglas, AK · 11 mi
998127a
Juneau, AK · 11 mi
998217a
Auke Bay, AK · 20 mi
998297a
Hoonah, AK · 48 mi
998507a
Juneau, AK · 48 mi

All 6 ZIP codes in Juneau → · Alaska planting zones →

Questions about 99801

What planting zone is ZIP code 99801?

ZIP code 99801 (Juneau, AK) is in USDA hardiness zone 6a on the 2023 map: the coldest night of an average winter reaches −10 to −5 °F (−23.3 to −20.6 °C).

When is the last frost in Juneau, AK?

The median last spring frost (32 °F) near 99801 is May 3; after May 18 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Annex Creek station.

When is the first frost in Juneau, AK?

The median first fall frost near 99801 is October 14, giving a median frost-free growing season of 164 days.

When should I plant tomatoes in 99801?

Start tomato seeds indoors around Mar 8 – Mar 22 and set transplants outside around May 10 – May 24, one to three weeks after the median last frost.

How much rain and snow does 99801 get?

About 88.5 inches of precipitation a year (NOAA 1991–2020 normals, Juneau-Douglas Wwtp station).

How hot do summers get in Juneau, AK?

The average high peaks at 59 °F in June, with about 0 days a year at 90 °F or more.

What kind of soil does 99801 have?

The USDA soil survey maps Typic Humicryepts at the center of ZIP 99801: moderately decomposed plant material, moderately well drained, pH about 3.9 (strongly acidic).

What kind of onions grow in Juneau, AK?

Long-day onions: the longest day near 99801 is 18 h 18 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99801 change?

Yes. The 2012 USDA map put 99801 in zone 6b; the 2023 map puts it in zone 6a. The newer map uses 1991–2020 data and more weather stations.