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

Planting zone for 99633 — Naknek, AK

ZIP code 99633 (Naknek, Bristol Bay County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 26 and the first fall frost September 15.

Where ZIP 99633 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.

Zone4b−25 to −20 °F

Coldest night−31.7 to −28.9 °C

Last frostMay 26

First frostSep 15

2012 zone4a

Was 4a on the 2012 map — half a zone warmer now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Naknek, 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 Naknek, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 26median — 50% chance of a later frost

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

First fall frostSeptember 15median — 10% chance by Aug 31

Growing season111 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around September 27.

From the NOAA station King Salmon, AK — 12 miles away, elevation 62 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 99633

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 14 – Apr 28

SpinachSow outdoors · Apr 14 – May 5

Broccoli, cabbageStart indoors · Mar 17 – Mar 31

Broccoli, cabbageTransplant · May 5 – May 19

Onion setsPlant outdoors · Apr 28 – May 12

PotatoesPlant outdoors · May 5 – May 19

LettuceSow outdoors · Apr 28 – May 12

Carrots, beetsSow outdoors · May 5 – May 19

TomatoesStart indoors · Mar 31 – Apr 14

TomatoesTransplant · Jun 2 – Jun 16

Peppers, eggplantStart indoors · Mar 17 – Mar 31

Peppers, eggplantTransplant · Jun 9 – Jun 23

BeansSow outdoors · Jun 2 – Jun 16

Sweet cornSow outdoors · Jun 2 – Jun 16

Cucumbers, squashSow outdoors · Jun 2 – Jun 16

Fall lettuce, spinachSow outdoors · Jul 21 – Aug 4

GarlicPlant cloves · Sep 1 – Oct 6

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 26) and first fall frost (Sep 15) 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 4b in Alaska

260 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −25 °F or colder — the bottom of zone 4b. 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 Naknek, AK.

Soil in Naknek, AK

The soil mapped at the center of ZIP 99633 is E36-maritime scrub-ashy till slopes — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer

pH4.4strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter80%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Bristol Bay-Northern Alaska Peninsula Lowlands-Maritime Upland-Glaciated Plains, Ash Influenced.

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 99633; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Naknek, AK

Summer high65 °Faverage high, July

Winter low10 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights192nights a year at 32 °F or less

Growing degree days566base 50 °F — the season’s usable heat

Longest day18 h 26 mindaylight on June 21

Shortest day6 h 14 mindaylight on December 21

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

Precipitation21.4 inper year, rain and melted snow

Snowfall47 inper year; 84 days with snow on the ground

Average high and low, by month

Precipitation by month inches · ❄ = snowfall

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: King Salmon, AK (12 mi away); precipitation: King Salmon, AK (12 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

996704b

South Naknek, AK · 10 mi

New Stuyahok, AK · 51 mi

996134a

King Salmon, AK · 57 mi

996495a

Pilot Point, AK · 90 mi

Alaska planting zones →

Questions about 99633

What planting zone is ZIP code 99633?

ZIP code 99633 (Naknek, AK) is in USDA hardiness zone 4b on the 2023 map: the coldest night of an average winter reaches −25 to −20 °F (−31.7 to −28.9 °C).

When is the last frost in Naknek, AK?

The median last spring frost (32 °F) near 99633 is May 26; after June 11 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, King Salmon station.

When is the first frost in Naknek, AK?

The median first fall frost near 99633 is September 15, giving a median frost-free growing season of 111 days.

When should I plant tomatoes in 99633?

Start tomato seeds indoors around Mar 31 – Apr 14 and set transplants outside around Jun 2 – Jun 16, one to three weeks after the median last frost.

How much rain and snow does 99633 get?

About 21.4 inches of precipitation a year and 47 inches of snowfall (NOAA 1991–2020 normals, King Salmon station).

How hot do summers get in Naknek, AK?

The average high peaks at 65 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99633 have?

The USDA soil survey maps E36-maritime scrub-ashy till slopes at the center of ZIP 99633: slightly decomposed plant material, well drained, pH about 4.4 (strongly acidic).

What kind of onions grow in Naknek, AK?

Long-day onions: the longest day near 99633 is 18 h 26 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99633 change?

Yes. The 2012 USDA map put 99633 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.