Data: 2023 USDA zones (PRISM/OSU) · NOAA 1991–2020 normals · updated Oct 29, 2026

Planting zone for 99748 — Kaltag, AK

ZIP code 99748 (Kaltag, Yukon-Koyukuk (CA) County) is in USDA zone 2a: the coldest winter night averages −50 to −45 °F. The median last spring frost is May 25 and the first fall frost September 3.

Where ZIP 99748 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.

Zone2a−50 to −45 °F

Coldest night−45.6 to −42.8 °C

Last frostMay 25

First frostSep 3

2012 zone2a

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 2a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kaltag, 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 Kaltag, AK

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostMay 25median — 50% chance of a later frost

Safe for tender plantsJune 11only 10% chance of frost after

First fall frostSeptember 3median — 10% chance by Aug 18

Growing season101 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 12 and returns around September 17.

From the NOAA station Kaltag Airport, AK — within 1 mile, elevation 180 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 99748

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 13 – Apr 27

SpinachSow outdoors · Apr 13 – May 4

Broccoli, cabbageStart indoors · Mar 16 – Mar 30

Broccoli, cabbageTransplant · May 4 – May 18

Onion setsPlant outdoors · Apr 27 – May 11

PotatoesPlant outdoors · May 4 – May 18

LettuceSow outdoors · Apr 27 – May 11

Carrots, beetsSow outdoors · May 4 – May 18

TomatoesStart indoors · Mar 30 – Apr 13

TomatoesTransplant · Jun 1 – Jun 15

Peppers, eggplantStart indoors · Mar 16 – Mar 30

Peppers, eggplantTransplant · Jun 8 – Jun 22

BeansSow outdoors · Jun 1 – Jun 15

Sweet cornSow outdoors · Jun 1 – Jun 15

Cucumbers, squashSow outdoors · Jun 1 – Jun 15

Fall lettuce, spinachSow outdoors · Jul 9 – Jul 23

GarlicPlant cloves · Aug 20 – Sep 24

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 25) and first fall frost (Sep 3) 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 2a in Alaska

44 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −50 °F or colder — the bottom of zone 2a. Each links to its USDA PLANTS profile.

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 Kaltag, AK.

Soil in Kaltag, AK

The soil mapped at the center of ZIP 99748 is E30-boreal taiga-silty frozen colluvial slopes — peat, poorly drained.

TexturePeattop layer

DrainagePoorly drainedconsider raised beds

Organic matter75%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Yukon-Kuskokwim Highlands-Boreal Upland-Valleys.

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 99748; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kaltag, AK

Summer high69 °Faverage high, June

Winter low−12 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights234nights a year at 32 °F or less

Growing degree days747base 50 °F — the season’s usable heat

Longest day21 h 18 mindaylight on June 21

Shortest day4 h 01 mindaylight on December 21

Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)

Precipitation21.5 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

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

Nearby ZIP codes

2 of the 4 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

997652a

Nulato, AK · 35 mi

996843b

Unalakleet, AK · 46 mi

997542a

Koyukuk, AK · 52 mi

995903a

Grayling, AK · 106 mi

Alaska planting zones →

Questions about 99748

What planting zone is ZIP code 99748?

ZIP code 99748 (Kaltag, AK) is in USDA hardiness zone 2a on the 2023 map: the coldest night of an average winter reaches −50 to −45 °F (−45.6 to −42.8 °C).

When is the last frost in Kaltag, AK?

The median last spring frost (32 °F) near 99748 is May 25; after June 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Kaltag Airport station.

When is the first frost in Kaltag, AK?

The median first fall frost near 99748 is September 3, giving a median frost-free growing season of 101 days.

When should I plant tomatoes in 99748?

Start tomato seeds indoors around Mar 30 – Apr 13 and set transplants outside around Jun 1 – Jun 15, one to three weeks after the median last frost.

How much rain and snow does 99748 get?

About 21.5 inches of precipitation a year (NOAA 1991–2020 normals, Kaltag Airport station).

How hot do summers get in Kaltag, AK?

The average high peaks at 69 °F in June, with about 0 days a year at 90 °F or more.

What kind of soil does 99748 have?

The USDA soil survey maps E30-boreal taiga-silty frozen colluvial slopes at the center of ZIP 99748: peat, poorly drained.

What kind of onions grow in Kaltag, AK?

Long-day onions: the longest day near 99748 is 21 h 18 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).