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

Planting zone for 99583 — False Pass, AK

ZIP code 99583 (False Pass, Aleutians East County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is May 25 and the first fall frost October 4.

Where ZIP 99583 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.

Zone7a0 to 5 °F

Coldest night−17.8 to −15 °C

Last frostMay 25

First frostOct 4

2012 zone7a

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 7a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for False Pass, 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 False Pass, 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 10only 10% chance of frost after

First fall frostOctober 4median — 10% chance by Sep 20

Growing season131 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 8 and returns around October 21.

From the NOAA station Cold Bay Airport, AK — 35 miles away, elevation 79 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 99583

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 · Aug 9 – Aug 23

GarlicPlant cloves · Sep 20 – Oct 25

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 25) and first fall frost (Oct 4) 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 7a in Alaska

289 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive 0 °F or colder — the bottom of zone 7a. 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 False Pass, AK.

Soil in False Pass, AK

The soil mapped at the center of ZIP 99583 is E25-Maritime tall scrub-sandy volcanic slopes — slightly decomposed plant material, somewhat excessively drained.

TextureSlightly decomposed plant materialtop layer

pH6.8neutral; most vegetables like 6.0–7.0

DrainageSomewhat excessively drainednatural drainage class

Organic matter75%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Southern Alaska Peninsula Mountains-Maritime Upland-Volcanic Mountains and Lowland-Flood Plains and Stream Terraces.

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 99583; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in False Pass, AK

Summer high57 °Faverage high, August

Winter low24 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights148nights a year at 32 °F or less

Growing degree days195base 50 °F — the season’s usable heat

Longest day17 h 21 mindaylight on June 21

Shortest day7 h 11 mindaylight on December 21

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

Precipitation42.7 inper year, rain and melted snow

Snowfall67 inper year; 67 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: Cold Bay Airport, AK (35 mi away); precipitation: Cold Bay Airport, AK (35 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 2 nearest ZIP codes share zone 7a.

995717a

Cold Bay, AK · 35 mi

996127a

King Cove, AK · 45 mi

Alaska planting zones →

Questions about 99583

What planting zone is ZIP code 99583?

ZIP code 99583 (False Pass, AK) is in USDA hardiness zone 7a on the 2023 map: the coldest night of an average winter reaches 0 to 5 °F (−17.8 to −15 °C).

When is the last frost in False Pass, AK?

The median last spring frost (32 °F) near 99583 is May 25; after June 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cold Bay Airport station.

When is the first frost in False Pass, AK?

The median first fall frost near 99583 is October 4, giving a median frost-free growing season of 131 days.

When should I plant tomatoes in 99583?

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 99583 get?

About 42.7 inches of precipitation a year and 67 inches of snowfall (NOAA 1991–2020 normals, Cold Bay Airport station).

How hot do summers get in False Pass, AK?

The average high peaks at 57 °F in August, with about 0 days a year at 90 °F or more.

What kind of soil does 99583 have?

The USDA soil survey maps E25-Maritime tall scrub-sandy volcanic slopes at the center of ZIP 99583: slightly decomposed plant material, somewhat excessively drained, pH about 6.8 (neutral).

What kind of onions grow in False Pass, AK?

Long-day onions: the longest day near 99583 is 17 h 21 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).