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

Planting zone for 99750 — Kivalina, AK

ZIP code 99750 (Kivalina, Northwest Arctic County) is in USDA zone 3a: the coldest winter night averages −40 to −35 °F. The median last spring frost is June 10 and the first fall frost September 11.

Where ZIP 99750 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.

Zone3a−40 to −35 °F

Coldest night−40 to −37.2 °C

Last frostJun 10

First frostSep 11

2012 zone3a

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 3a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kivalina, 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 Kivalina, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 10median — 50% chance of a later frost

Safe for tender plantsJune 23only 10% chance of frost after

First fall frostSeptember 11median — 10% chance by Aug 26

Growing season92 daysfrost-free, median

A hard freeze (28 °F) usually ends around June 1 and returns around September 24.

From the NOAA station Kivalina Airport, AK — within 1 mile, elevation 10 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 99750

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 29 – May 13

SpinachSow outdoors · Apr 29 – May 20

Broccoli, cabbageStart indoors · Apr 1 – Apr 15

Broccoli, cabbageTransplant · May 20 – Jun 3

Onion setsPlant outdoors · May 13 – May 27

PotatoesPlant outdoors · May 20 – Jun 3

LettuceSow outdoors · May 13 – May 27

Carrots, beetsSow outdoors · May 20 – Jun 3

TomatoesStart indoors · Apr 15 – Apr 29

TomatoesTransplant · Jun 17 – Jul 1

Peppers, eggplantStart indoors · Apr 1 – Apr 15

Peppers, eggplantTransplant · Jun 24 – Jul 8

BeansSow outdoors · Jun 17 – Jul 1

Sweet cornSow outdoors · Jun 17 – Jul 1

Cucumbers, squashSow outdoors · Jun 17 – Jul 1

Fall lettuce, spinachSow outdoors · Jul 17 – Jul 31

GarlicPlant cloves · Aug 28 – Oct 2

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 10) and first fall frost (Sep 11) 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 3a in Alaska

80 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −40 °F or colder — the bottom of zone 3a. 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 Kivalina, AK.

Soil in Kivalina, AK

The soil mapped at the center of ZIP 99750 is E42-arctic wet meadow-silty low coastal plains — slightly decomposed plant material, very poorly drained.

TextureSlightly decomposed plant materialtop layer

pH4.0strongly acidic; most vegetables like 6.0–7.0

DrainageVery poorly drainedconsider raised beds

Organic matter75%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Northern Seward Peninsula-Selawik Lowlands-Water, Saline.

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 99750; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kivalina, AK

Summer high56 °Faverage high, July

Winter low−9 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights244nights a year at 32 °F or less

Growing degree days175base 50 °F — the season’s usable heat

Longest day24 h 00 mindaylight on June 21

Shortest day0 h 00 mindaylight on December 21

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

Precipitation9.7 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: Kivalina Airport, AK (within 1 mile); precipitation: Kivalina Airport, AK (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 3 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

997612a

Noatak, AK · 41 mi

997663a

Point Hope, AK · 54 mi

997363a

Deering, AK · 124 mi

Alaska planting zones →

Questions about 99750

What planting zone is ZIP code 99750?

ZIP code 99750 (Kivalina, AK) is in USDA hardiness zone 3a on the 2023 map: the coldest night of an average winter reaches −40 to −35 °F (−40 to −37.2 °C).

When is the last frost in Kivalina, AK?

The median last spring frost (32 °F) near 99750 is June 10; after June 23 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Kivalina Airport station.

When is the first frost in Kivalina, AK?

The median first fall frost near 99750 is September 11, giving a median frost-free growing season of 92 days.

When should I plant tomatoes in 99750?

Start tomato seeds indoors around Apr 15 – Apr 29 and set transplants outside around Jun 17 – Jul 1, one to three weeks after the median last frost.

How much rain and snow does 99750 get?

About 9.7 inches of precipitation a year (NOAA 1991–2020 normals, Kivalina Airport station).

How hot do summers get in Kivalina, AK?

The average high peaks at 56 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99750 have?

The USDA soil survey maps E42-arctic wet meadow-silty low coastal plains at the center of ZIP 99750: slightly decomposed plant material, very poorly drained, pH about 4.0 (strongly acidic).

What kind of onions grow in Kivalina, AK?

Long-day onions: the longest day near 99750 is 24 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).