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

Planting zone for 99566 — Chitina, AK

ZIP code 99566 (Chitina, Copper River Census Area County) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 31 and the first fall frost September 3.

Where ZIP 99566 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 31

First frostSep 3

2012 zone3b

Was 3b 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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Chitina, 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 Chitina, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 31median — 50% chance of a later frost

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

First fall frostSeptember 3median — 10% chance by Aug 20

Growing season95 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 16 and returns around September 17.

From the NOAA station Silver Lake, AK — 55 miles away, elevation 1,201 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 99566

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 19 – May 3

SpinachSow outdoors · Apr 19 – May 10

Broccoli, cabbageStart indoors · Mar 22 – Apr 5

Broccoli, cabbageTransplant · May 10 – May 24

Onion setsPlant outdoors · May 3 – May 17

PotatoesPlant outdoors · May 10 – May 24

LettuceSow outdoors · May 3 – May 17

Carrots, beetsSow outdoors · May 10 – May 24

TomatoesStart indoors · Apr 5 – Apr 19

TomatoesTransplant · Jun 7 – Jun 21

Peppers, eggplantStart indoors · Mar 22 – Apr 5

Peppers, eggplantTransplant · Jun 14 – Jun 28

BeansSow outdoors · Jun 7 – Jun 21

Sweet cornSow outdoors · Jun 7 – Jun 21

Cucumbers, squashSow outdoors · Jun 7 – Jun 21

Fall lettuce, spinachSow outdoors · Jul 9 – Jul 23

GarlicPlant cloves · Aug 20 – Sep 24

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 31) and first fall frost (Sep 3) 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 Chitina, AK.

Soil in Chitina, AK

The soil mapped at the center of ZIP 99566 is E28-boreal subalpine woodland-gravelly colluvial slopes — slightly decomposed plant material, somewhat poorly drained.

TextureSlightly decomposed plant materialtop layer

DrainageSomewhat poorly drainedconsider raised beds

Organic matter75%high

Hydrologic groupB/Dmoderate when drained; wet otherwise

Map unit: Interior Alaska Mountains-Boreal Subalpine and Alpine-Rugged 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 99566; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Chitina, AK

Summer high71 °Faverage high, July

Winter low−9 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights256nights a year at 32 °F or less

Growing degree days532base 50 °F — the season’s usable heat

Longest day19 h 24 mindaylight on June 21

Shortest day5 h 26 mindaylight on December 21

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

Precipitation13.9 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: Mccarthy 3 Sw, AK (16 mi away); precipitation: May Creek, AK (6 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 2 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

997642a

Northway, AK · 101 mi

995862b

Gakona, AK · 112 mi

Alaska planting zones →

Questions about 99566

What planting zone is ZIP code 99566?

ZIP code 99566 (Chitina, 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 Chitina, AK?

The median last spring frost (32 °F) near 99566 is May 31; after June 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Silver Lake station.

When is the first frost in Chitina, AK?

The median first fall frost near 99566 is September 3, giving a median frost-free growing season of 95 days.

When should I plant tomatoes in 99566?

Start tomato seeds indoors around Apr 5 – Apr 19 and set transplants outside around Jun 7 – Jun 21, one to three weeks after the median last frost.

How much rain and snow does 99566 get?

About 13.9 inches of precipitation a year (NOAA 1991–2020 normals, May Creek station).

How hot do summers get in Chitina, AK?

The average high peaks at 71 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99566 have?

The USDA soil survey maps E28-boreal subalpine woodland-gravelly colluvial slopes at the center of ZIP 99566: slightly decomposed plant material, somewhat poorly drained.

What kind of onions grow in Chitina, AK?

Long-day onions: the longest day near 99566 is 19 h 24 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99566 change?

Yes. The 2012 USDA map put 99566 in zone 3b; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.