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

Planting zone for 99811 — Juneau, AK

ZIP code 99811 (Juneau, Juneau City and Borough) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is April 20 and the first fall frost October 22.

Where ZIP 99811 is

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.

Zone7a0 to 5 °F
Coldest night−17.8 to −15 °C
Last frostApr 20
First frostOct 22
2012 zone7a

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 7a 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 frostApril 20median — 50% chance of a later frost
Safe for tender plantsMay 5only 10% chance of frost after
First fall frostOctober 22median — 10% chance by Oct 5
Growing season183 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 2 and returns around November 8.

From the NOAA station Juneau Dwtn, AK — within 1 mile, elevation 49 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 99811

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Mar 9 – Mar 23
SpinachSow outdoors · Mar 9 – Mar 30
Broccoli, cabbageStart indoors · Feb 9 – Feb 23
Broccoli, cabbageTransplant · Mar 30 – Apr 13
Onion setsPlant outdoors · Mar 23 – Apr 6
PotatoesPlant outdoors · Mar 30 – Apr 13
LettuceSow outdoors · Mar 23 – Apr 6
Carrots, beetsSow outdoors · Mar 30 – Apr 13
TomatoesStart indoors · Feb 23 – Mar 9
TomatoesTransplant · Apr 27 – May 11
Peppers, eggplantStart indoors · Feb 9 – Feb 23
Peppers, eggplantTransplant · May 4 – May 18
BeansSow outdoors · Apr 27 – May 11
Sweet cornSow outdoors · Apr 27 – May 11
Cucumbers, squashSow outdoors · Apr 27 – May 11
Fall lettuce, spinachSow outdoors · Aug 27 – Sep 10
GarlicPlant cloves · Oct 8 – Nov 12
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Apr 20) and first fall frost (Oct 22) 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 7a in Alaska

289 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 50

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 125

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 89

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 center of ZIP 99811 is mapped as Urbanland: 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 99811; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Juneau, AK

Summer high63 °Faverage high, July
Winter low27 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights105nights a year at 32 °F or less
Growing degree days750base 50 °F — the season’s usable heat
Longest day18 h 17 mindaylight on June 21
Shortest day6 h 22 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation89.6 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°32 °FJanuary: average high 34 °F, low 27 °F 34°27° JanFebruary: average high 37 °F, low 28 °F 37°28° FebMarch: average high 39 °F, low 30 °F 39°30° MarApril: average high 49 °F, low 36 °F 49°36° AprMay: average high 57 °F, low 43 °F 57°43° MayJune: average high 62 °F, low 49 °F 62°49° JunJuly: average high 63 °F, low 52 °F 63°52° JulAugust: average high 62 °F, low 51 °F 62°51° AugSeptember: average high 56 °F, low 46 °F 56°46° SepOctober: average high 48 °F, low 39 °F 48°39° OctNovember: average high 40 °F, low 32 °F 40°32° NovDecember: average high 36 °F, low 29 °F 36°29° Dec

Precipitation by month inches

0″2″4″6″8″10″12″January: 5.88 in precipitation 5.9 JanFebruary: 5.16 in precipitation 5.2 FebMarch: 6.17 in precipitation 6.2 MarApril: 4.76 in precipitation 4.8 AprMay: 5.09 in precipitation 5.1 MayJune: 4.90 in precipitation 4.9 JunJuly: 6.21 in precipitation 6.2 JulAugust: 7.76 in precipitation 7.8 AugSeptember: 12.71 in precipitation 12.7 SepOctober: 12.27 in precipitation 12.3 OctNovember: 8.75 in precipitation 8.8 NovDecember: 9.93 in precipitation 9.9 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Juneau Dwtn, AK (within 1 mile); precipitation: Juneau Dwtn, AK (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

998027a
Juneau, AK · <1 mi
998037a
Juneau, AK · <1 mi
998247a
Douglas, AK · 3 mi
998127a
Juneau, AK · 3 mi
998016a
Juneau, AK · 10 mi
998217a
Auke Bay, AK · 14 mi
998297a
Hoonah, AK · 38 mi
998507a
Juneau, AK · 41 mi

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

Questions about 99811

What planting zone is ZIP code 99811?

ZIP code 99811 (Juneau, AK) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in Juneau, AK?

The median last spring frost (32 °F) near 99811 is April 20; after May 5 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Juneau Dwtn station.

When is the first frost in Juneau, AK?

The median first fall frost near 99811 is October 22, giving a median frost-free growing season of 183 days.

When should I plant tomatoes in 99811?

Start tomato seeds indoors around Feb 23 – Mar 9 and set transplants outside around Apr 27 – May 11, one to three weeks after the median last frost.

How much rain and snow does 99811 get?

About 89.6 inches of precipitation a year (NOAA 1991–2020 normals, Juneau Dwtn station).

How hot do summers get in Juneau, AK?

The average high peaks at 63 °F in July, with about 0 days a year at 90 °F or more.

What kind of onions grow in Juneau, AK?

Long-day onions: the longest day near 99811 is 18 h 17 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).