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

Planting zone for 99693 — Whittier, AK

ZIP code 99693 (Whittier, Chugach Census Area County) is in USDA zone 7a: the coldest winter night averages 0 to 5 °F. The median last spring frost is May 20 and the first fall frost October 9.

Where ZIP 99693 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 20

First frostOct 9

2012 zone6a

Was 6a on the 2012 map — a full zone warmer now. 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 Whittier, 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 Whittier, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 20median — 50% chance of a later frost

Safe for tender plantsJune 1only 10% chance of frost after

First fall frostOctober 9median — 10% chance by Sep 26

Growing season142 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 5 and returns around October 23.

From the NOAA station Wally Noerenberg Hatchery, AK — 4 miles away, elevation 36 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 99693

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 8 – Apr 22

SpinachSow outdoors · Apr 8 – Apr 29

Broccoli, cabbageStart indoors · Mar 11 – Mar 25

Broccoli, cabbageTransplant · Apr 29 – May 13

Onion setsPlant outdoors · Apr 22 – May 6

PotatoesPlant outdoors · Apr 29 – May 13

LettuceSow outdoors · Apr 22 – May 6

Carrots, beetsSow outdoors · Apr 29 – May 13

TomatoesStart indoors · Mar 25 – Apr 8

TomatoesTransplant · May 27 – Jun 10

Peppers, eggplantStart indoors · Mar 11 – Mar 25

Peppers, eggplantTransplant · Jun 3 – Jun 17

BeansSow outdoors · May 27 – Jun 10

Sweet cornSow outdoors · May 27 – Jun 10

Cucumbers, squashSow outdoors · May 27 – Jun 10

Fall lettuce, spinachSow outdoors · Aug 14 – Aug 28

GarlicPlant cloves · Sep 25 – Oct 30

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 20) and first fall frost (Oct 9) 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 Whittier, AK.

Soil in Whittier, AK

The soil mapped at the center of ZIP 99693 is E20-maritime forest-loamy colluvial slopes, shallow — moderately decomposed plant material, moderately well drained.

TextureModerately decomposed plant materialtop layer

pH5.5moderately acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter75%high

Hydrologic groupCwater soaks in slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Alexander Archipelago-Gulf of Alaska Coast-Maritime Upland and Subalpine-Rounded Mountains.

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 99693; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Whittier, AK

Summer high63 °Faverage high, July

Winter low20 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights143nights a year at 32 °F or less

Growing degree days521base 50 °F — the season’s usable heat

Longest day19 h 13 mindaylight on June 21

Shortest day5 h 35 mindaylight on December 21

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

Precipitation157.4 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: Wally Noerenberg Hatchery, AK (4 mi away); precipitation: Esther Island, AK (4 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

8 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

Eagle River, AK · 47 mi

Alaska planting zones →

Questions about 99693

What planting zone is ZIP code 99693?

ZIP code 99693 (Whittier, 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 Whittier, AK?

The median last spring frost (32 °F) near 99693 is May 20; after June 1 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Wally Noerenberg Hatchery station.

When is the first frost in Whittier, AK?

The median first fall frost near 99693 is October 9, giving a median frost-free growing season of 142 days.

When should I plant tomatoes in 99693?

Start tomato seeds indoors around Mar 25 – Apr 8 and set transplants outside around May 27 – Jun 10, one to three weeks after the median last frost.

How much rain and snow does 99693 get?

About 157.4 inches of precipitation a year (NOAA 1991–2020 normals, Esther Island station).

How hot do summers get in Whittier, AK?

The average high peaks at 63 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99693 have?

The USDA soil survey maps E20-maritime forest-loamy colluvial slopes, shallow at the center of ZIP 99693: moderately decomposed plant material, moderately well drained, pH about 5.5 (moderately acidic).

What kind of onions grow in Whittier, AK?

Long-day onions: the longest day near 99693 is 19 h 13 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99693 change?

Yes. The 2012 USDA map put 99693 in zone 6a; the 2023 map puts it in zone 7a. The newer map uses 1991–2020 data and more weather stations.