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

Planting zone for 99626 — Lower Kalskag, AK

ZIP code 99626 (Lower Kalskag, Bethel Census Area County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 21 and the first fall frost September 22.

Where ZIP 99626 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 21
First frostSep 22
2012 zone2b

Was 2b on the 2012 map — a full zone 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 Lower Kalskag, 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 Lower Kalskag, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 21median — 50% chance of a later frost
Safe for tender plantsJune 2only 10% chance of frost after
First fall frostSeptember 22median — 10% chance by Sep 7
Growing season122 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 11 and returns around October 1.

From the NOAA station Bethel Airport, AK — 70 miles away, elevation 102 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 99626

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 9 – Apr 23
SpinachSow outdoors · Apr 9 – Apr 30
Broccoli, cabbageStart indoors · Mar 12 – Mar 26
Broccoli, cabbageTransplant · Apr 30 – May 14
Onion setsPlant outdoors · Apr 23 – May 7
PotatoesPlant outdoors · Apr 30 – May 14
LettuceSow outdoors · Apr 23 – May 7
Carrots, beetsSow outdoors · Apr 30 – May 14
TomatoesStart indoors · Mar 26 – Apr 9
TomatoesTransplant · May 28 – Jun 11
Peppers, eggplantStart indoors · Mar 12 – Mar 26
Peppers, eggplantTransplant · Jun 4 – Jun 18
BeansSow outdoors · May 28 – Jun 11
Sweet cornSow outdoors · May 28 – Jun 11
Cucumbers, squashSow outdoors · May 28 – Jun 11
Fall lettuce, spinachSow outdoors · Jul 28 – Aug 11
GarlicPlant cloves · Sep 8 – Oct 13
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 21) and first fall frost (Sep 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 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 Lower Kalskag, AK.

Soil in Lower Kalskag, AK

The soil mapped at the center of ZIP 99626 is 38-Ulesqiirluni — moderately decomposed plant material, moderately well drained.

TextureModerately decomposed plant materialtop layer
pH6.3slightly acidic; most vegetables like 6.0–7.0
DrainageModerately well drainednatural drainage class
Organic matter75%high
Hydrologic groupBwater soaks in moderately
Farmland classNot prime farmlandUSDA classification

Map unit: Ulesqiirluni silt, 0 to 1 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 99626; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Lower Kalskag, AK

Summer high64 °Faverage high, July
Winter low1 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights214nights a year at 32 °F or less
Growing degree days501base 50 °F — the season’s usable heat
Longest day19 h 31 mindaylight on June 21
Shortest day5 h 20 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Average high and low, by month

−10°0°10°20°30°40°50°60°70°32 °FJanuary: average high 13 °F, low 1 °F 13°1° JanFebruary: average high 20 °F, low 7 °F 20°7° FebMarch: average high 22 °F, low 7 °F 22°7° MarApril: average high 37 °F, low 21 °F 37°21° AprMay: average high 52 °F, low 34 °F 52°34° MayJune: average high 62 °F, low 45 °F 62°45° JunJuly: average high 64 °F, low 49 °F 64°49° JulAugust: average high 61 °F, low 47 °F 61°47° AugSeptember: average high 53 °F, low 39 °F 53°39° SepOctober: average high 38 °F, low 26 °F 38°26° OctNovember: average high 24 °F, low 13 °F 24°13° NovDecember: average high 16 °F, low 4 °F 16°4° Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Bethel Airport, AK (70 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

996073b
Kalskag, AK · 2 mi
996793b
Tuluksak, AK · 34 mi
996573b
Russian Mission, AK · 42 mi
996023a
Holy Cross, AK · 49 mi
995523b
Akiak, AK · 51 mi
995513b
Akiachak, AK · 54 mi
996214a
Kwethluk, AK · 61 mi
995583b
Anvik, AK · 77 mi

Alaska planting zones →

Questions about 99626

What planting zone is ZIP code 99626?

ZIP code 99626 (Lower Kalskag, 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 Lower Kalskag, AK?

The median last spring frost (32 °F) near 99626 is May 21; after June 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Bethel Airport station.

When is the first frost in Lower Kalskag, AK?

The median first fall frost near 99626 is September 22, giving a median frost-free growing season of 122 days.

When should I plant tomatoes in 99626?

Start tomato seeds indoors around Mar 26 – Apr 9 and set transplants outside around May 28 – Jun 11, one to three weeks after the median last frost.

How hot do summers get in Lower Kalskag, AK?

The average high peaks at 64 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99626 have?

The USDA soil survey maps 38-Ulesqiirluni at the center of ZIP 99626: moderately decomposed plant material, moderately well drained, pH about 6.3 (slightly acidic).

What kind of onions grow in Lower Kalskag, AK?

Long-day onions: the longest day near 99626 is 19 h 31 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99626 change?

Yes. The 2012 USDA map put 99626 in zone 2b; the 2023 map puts it in zone 3b. The newer map uses 1991–2020 data and more weather stations.