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

Planting zone for 99516 — Anchorage, AK

ZIP code 99516 (Anchorage, Anchorage Municipality) is in USDA zone 5b: the coldest winter night averages −15 to −10 °F. The median last spring frost is May 18 and the first fall frost September 23.

Where ZIP 99516 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.

Zone5b−15 to −10 °F

Coldest night−26.1 to −23.3 °C

Last frostMay 18

First frostSep 23

2012 zone4b

Was 4b 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 5b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Anchorage, 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 Anchorage, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 18median — 50% chance of a later frost

Safe for tender plantsMay 31only 10% chance of frost after

First fall frostSeptember 23median — 10% chance by Sep 8

Growing season125 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 4 and returns around October 2.

From the NOAA station Glen Alps, AK — within 1 mile, elevation 2,202 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 99516

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 6 – Apr 20

SpinachSow outdoors · Apr 6 – Apr 27

Broccoli, cabbageStart indoors · Mar 9 – Mar 23

Broccoli, cabbageTransplant · Apr 27 – May 11

Onion setsPlant outdoors · Apr 20 – May 4

PotatoesPlant outdoors · Apr 27 – May 11

LettuceSow outdoors · Apr 20 – May 4

Carrots, beetsSow outdoors · Apr 27 – May 11

TomatoesStart indoors · Mar 23 – Apr 6

TomatoesTransplant · May 25 – Jun 8

Peppers, eggplantStart indoors · Mar 9 – Mar 23

Peppers, eggplantTransplant · Jun 1 – Jun 15

BeansSow outdoors · May 25 – Jun 8

Sweet cornSow outdoors · May 25 – Jun 8

Cucumbers, squashSow outdoors · May 25 – Jun 8

Fall lettuce, spinachSow outdoors · Jul 29 – Aug 12

GarlicPlant cloves · Sep 9 – Oct 14

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 18) and first fall frost (Sep 23) 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 5b in Alaska

282 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −15 °F or colder — the bottom of zone 5b. 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 Anchorage, AK.

Soil in Anchorage, AK

The soil mapped at the center of ZIP 99516 is Talkeetna — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer

pH4.7strongly acidic; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter35%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Talkeetna-Chugach-Deneka complex, 20 to 45 percent slopes.

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 99516; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Anchorage, AK

Summer high59 °Faverage high, July

Winter low14 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights212nights a year at 32 °F or less

Growing degree days281base 50 °F — the season’s usable heat

Longest day19 h 19 mindaylight on June 21

Shortest day5 h 30 mindaylight on December 21

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

Precipitation26 inper year, rain and melted snow

Snowfall162 inper year; 204 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: Glen Alps, AK (within 1 mile); precipitation: Glen Alps, AK (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

All 25 ZIP codes in Anchorage → · Alaska planting zones →

Questions about 99516

What planting zone is ZIP code 99516?

ZIP code 99516 (Anchorage, AK) is in USDA hardiness zone 5b on the 2023 map: the coldest night of an average winter reaches −15 to −10 °F (−26.1 to −23.3 °C).

When is the last frost in Anchorage, AK?

The median last spring frost (32 °F) near 99516 is May 18; after May 31 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Glen Alps station.

When is the first frost in Anchorage, AK?

The median first fall frost near 99516 is September 23, giving a median frost-free growing season of 125 days.

When should I plant tomatoes in 99516?

Start tomato seeds indoors around Mar 23 – Apr 6 and set transplants outside around May 25 – Jun 8, one to three weeks after the median last frost.

How much rain and snow does 99516 get?

About 26 inches of precipitation a year and 162 inches of snowfall (NOAA 1991–2020 normals, Glen Alps station).

How hot do summers get in Anchorage, AK?

The average high peaks at 59 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99516 have?

The USDA soil survey maps Talkeetna at the center of ZIP 99516: slightly decomposed plant material, well drained, pH about 4.7 (strongly acidic).

What kind of onions grow in Anchorage, AK?

Long-day onions: the longest day near 99516 is 19 h 19 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99516 change?

Yes. The 2012 USDA map put 99516 in zone 4b; the 2023 map puts it in zone 5b. The newer map uses 1991–2020 data and more weather stations.