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

Planting zone for 99622 — Kwigillingok, AK

ZIP code 99622 (Kwigillingok, Bethel Census Area County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 21 and the first fall frost September 22.

Where ZIP 99622 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.

Zone4a−30 to −25 °F

Coldest night−34.4 to −31.7 °C

Last frostMay 21

First frostSep 22

2012 zone4a

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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Kwigillingok, 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 Kwigillingok, 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 — 78 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 99622

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.

Soil in Kwigillingok, AK

The soil mapped at the center of ZIP 99622 is E38-maritime dwarf scrub-lichen-silty frozen coastal plains — peat, poorly drained.

TexturePeattop layer

pH4.8strongly acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter80%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Yukon-Kuskokwim Coastal Plain-Maritime Lowland-Coastal Plains, Mid-Level.

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 99622; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Kwigillingok, 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 day18 h 49 mindaylight on June 21

Shortest day5 h 54 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

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Bethel Airport, AK (78 mi away). 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.

995454a

Kongiganak, AK · 11 mi

996144a

Kipnuk, AK · 32 mi

996804a

Tuntutuliak, AK · 37 mi

995614a

Chefornak, AK · 42 mi

995784a

Eek, AK · 46 mi

996554b

Quinhagak, AK · 46 mi

Alaska planting zones →

Questions about 99622

What planting zone is ZIP code 99622?

ZIP code 99622 (Kwigillingok, AK) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

When is the last frost in Kwigillingok, AK?

The median last spring frost (32 °F) near 99622 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 Kwigillingok, AK?

The median first fall frost near 99622 is September 22, giving a median frost-free growing season of 122 days.

When should I plant tomatoes in 99622?

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 Kwigillingok, 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 99622 have?

The USDA soil survey maps E38-maritime dwarf scrub-lichen-silty frozen coastal plains at the center of ZIP 99622: peat, poorly drained, pH about 4.8 (strongly acidic).

What kind of onions grow in Kwigillingok, AK?

Long-day onions: the longest day near 99622 is 18 h 49 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).