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

Planting zone for 99835 — Sitka, AK

ZIP code 99835 (Sitka, Sitka City and Borough) is in USDA zone 7b: the coldest winter night averages 5 to 10 °F. The median last spring frost is May 3 and the first fall frost October 18.

Where ZIP 99835 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.

Zone7b5 to 10 °F
Coldest night−15 to −12.2 °C
Last frostMay 3
First frostOct 18
2012 zone8a

Was 8a 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 7b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Sitka, 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 Sitka, 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 19only 10% chance of frost after
First fall frostOctober 18median — 10% chance by Oct 1
Growing season166 daysfrost-free, median

A hard freeze (28 °F) usually ends around April 7 and returns around November 10.

From the NOAA station Sitka 1 Ne, AK — 13 miles away, elevation 79 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 99835

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 23 – Sep 6
GarlicPlant cloves · Oct 4 – Nov 8
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 3) and first fall frost (Oct 18) 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 7b in Alaska

289 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive 5 °F or colder — the bottom of zone 7b. 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 Sitka, AK.

Soil in Sitka, AK

The soil mapped at the center of ZIP 99835 is Tolstoi — moderately decomposed plant material, moderately well drained.

TextureModerately decomposed plant materialtop layer
pH3.8strongly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter80%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Tolstoi and Kaikli soils, alpine, 76 to 120 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 99835; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sitka, AK

Summer high62 °Faverage high, August
Winter low29 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights115nights a year at 32 °F or less
Growing degree days491base 50 °F — the season’s usable heat
Longest day17 h 53 mindaylight on June 21
Shortest day6 h 43 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation102.1 inper year, rain and melted snow

Average high and low, by month

20°30°40°50°60°70°32 °FJanuary: average high 37 °F, low 29 °F 37°29° JanFebruary: average high 39 °F, low 30 °F 39°30° FebMarch: average high 42 °F, low 30 °F 42°30° MarApril: average high 49 °F, low 34 °F 49°34° AprMay: average high 54 °F, low 39 °F 54°39° MayJune: average high 58 °F, low 45 °F 58°45° JunJuly: average high 60 °F, low 50 °F 60°50° JulAugust: average high 62 °F, low 50 °F 62°50° AugSeptember: average high 57 °F, low 45 °F 57°45° SepOctober: average high 49 °F, low 39 °F 49°39° OctNovember: average high 42 °F, low 33 °F 42°33° NovDecember: average high 38 °F, low 30 °F 38°30° Dec

Precipitation by month inches

0″2″4″6″8″10″12″14″January: 9.58 in precipitation 9.6 JanFebruary: 6.48 in precipitation 6.5 FebMarch: 6.43 in precipitation 6.4 MarApril: 5.01 in precipitation 5.0 AprMay: 4.05 in precipitation 4.0 MayJune: 3.63 in precipitation 3.6 JunJuly: 5.53 in precipitation 5.5 JulAugust: 9.61 in precipitation 9.6 AugSeptember: 13.78 in precipitation 13.8 SepOctober: 14.79 in precipitation 14.8 OctNovember: 12.14 in precipitation 12.1 NovDecember: 11.03 in precipitation 11.0 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Sitka 1 Ne, AK (13 mi away); precipitation: Sitka 1 Ne, AK (13 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

998307b
Kake, AK · 38 mi
998207a
Angoon, AK · 41 mi
998368a
Port Alexander, AK · 51 mi
999278a
Point Baker, AK · 70 mi
998417a
Tenakee Springs, AK · 71 mi
998297a
Hoonah, AK · 74 mi
998327a
Pelican, AK · 80 mi
998257a
Elfin Cove, AK · 91 mi

Alaska planting zones →

Questions about 99835

What planting zone is ZIP code 99835?

ZIP code 99835 (Sitka, AK) is in USDA hardiness zone 7b on the 2023 map: the coldest night of an average winter reaches 5 to 10 °F (−15 to −12.2 °C).

When is the last frost in Sitka, AK?

The median last spring frost (32 °F) near 99835 is May 3; after May 19 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Sitka 1 Ne station.

When is the first frost in Sitka, AK?

The median first fall frost near 99835 is October 18, giving a median frost-free growing season of 166 days.

When should I plant tomatoes in 99835?

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 99835 get?

About 102.1 inches of precipitation a year (NOAA 1991–2020 normals, Sitka 1 Ne station).

How hot do summers get in Sitka, AK?

The average high peaks at 62 °F in August, with about 0 days a year at 90 °F or more.

What kind of soil does 99835 have?

The USDA soil survey maps Tolstoi at the center of ZIP 99835: moderately decomposed plant material, moderately well drained, pH about 3.8 (strongly acidic).

What kind of onions grow in Sitka, AK?

Long-day onions: the longest day near 99835 is 17 h 53 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99835 change?

Yes. The 2012 USDA map put 99835 in zone 8a; the 2023 map puts it in zone 7b. The newer map uses 1991–2020 data and more weather stations.