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

Planting zone for 99572 — Cooper Landing, AK

ZIP code 99572 (Cooper Landing, Kenai Peninsula County) is in USDA zone 5a: the coldest winter night averages −20 to −15 °F. The median last spring frost is June 12 and the first fall frost September 1.

Where ZIP 99572 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.

Zone5a−20 to −15 °F
Coldest night−28.9 to −26.1 °C
Last frostJun 12
First frostSep 1
2012 zone4b

Was 4b 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 5a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Cooper Landing, 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 Cooper Landing, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostJune 12median — 50% chance of a later frost
Safe for tender plantsJuly 2only 10% chance of frost after
First fall frostSeptember 1median — 10% chance by Aug 14
Growing season78 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 26 and returns around September 15.

From the NOAA station Cooper Landing 5 W, AK — 3 miles away, elevation 374 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 99572

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · May 1 – May 15
SpinachSow outdoors · May 1 – May 22
Broccoli, cabbageStart indoors · Apr 3 – Apr 17
Broccoli, cabbageTransplant · May 22 – Jun 5
Onion setsPlant outdoors · May 15 – May 29
PotatoesPlant outdoors · May 22 – Jun 5
LettuceSow outdoors · May 15 – May 29
Carrots, beetsSow outdoors · May 22 – Jun 5
TomatoesStart indoors · Apr 17 – May 1
TomatoesTransplant · Jun 19 – Jul 3
Peppers, eggplantStart indoors · Apr 3 – Apr 17
Peppers, eggplantTransplant · Jun 26 – Jul 10
BeansSow outdoors · Jun 19 – Jul 3
Sweet cornSow outdoors · Jun 19 – Jul 3
Cucumbers, squashSow outdoors · Jun 19 – Jul 3
Fall lettuce, spinachSow outdoors · Jul 7 – Jul 21
GarlicPlant cloves · Aug 18 – Sep 22
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 12) and first fall frost (Sep 1) 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 5a in Alaska

275 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −20 °F or colder — the bottom of zone 5a. Each links to its USDA PLANTS profile.

Trees 14

Alaska cedar75 ft · blooms mid spring · low shade tolerance · to −22 °Fbalsam poplar80 ft · blooms late spring · high shade tolerance · to −79 °Fblack spruce65 ft · blooms late spring · low shade tolerance · to −79 °Flodgepole pine99 ft · blooms mid summer · high shade tolerance · to −70 °FPacific silver fir165 ft · blooms late spring · low shade tolerance · to −28 °Fpaper birch70 ft · blooms mid spring · high shade tolerance · to −62 °F

Shrubs 46

alpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °Falpine laurel1 ft · blooms late spring · low shade tolerance · to −28 °FBarclay's willow15 ft · high shade tolerance · to −43 °Fblack crowberry1 ft · blooms mid summer · high shade tolerance · to −43 °Fblack hawthorn15 ft · blooms mid spring · medium shade tolerance · to −47 °Fbog blueberry2 ft · blooms early summer · medium shade tolerance · to −38 °F

Wildflowers & perennials 119

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °Falpine aster0.3 ft · blooms early summer · medium shade tolerance · to −28 °Falpine bistort1 ft · blooms mid spring · high shade tolerance · to −38 °Falpine mountainsorrel1 ft · blooms mid summer · medium shade tolerance · to −43 °Falpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °FAmerican alpine speedwell1 ft · blooms summer · medium shade tolerance · to −28 °F

Grasses 87

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine timothy1.4 ft · blooms late spring · medium shade tolerance · to −43 °Farctic bluegrass2 ft · high shade tolerance · to −62 °Fawlfruit sedge4 ft · blooms mid spring · low shade tolerance · to −38 °Fbeaked sedge4 ft · blooms late spring · low shade tolerance · to −38 °F

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 Cooper Landing, AK.

Soil in Cooper Landing, AK

The soil mapped at the center of ZIP 99572 is E23-boreal alpine scrub-gravelly colluvial slopes — moderately decomposed plant material, well drained.

TextureModerately decomposed plant materialtop layer
pH5.0strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter75%high
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Cook Inlet Mountains-Boreal Alpine-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 99572; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Cooper Landing, AK

Summer high69 °Faverage high, July
Winter low9 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights219nights a year at 32 °F or less
Growing degree days613base 50 °F — the season’s usable heat
Longest day19 h 05 mindaylight on June 21
Shortest day5 h 42 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation40.5 inper year, rain and melted snow

Average high and low, by month

0°10°20°30°40°50°60°70°80°32 °FJanuary: average high 24 °F, low 9 °F 24°9° JanFebruary: average high 31 °F, low 14 °F 31°14° FebMarch: average high 37 °F, low 14 °F 37°14° MarApril: average high 48 °F, low 26 °F 48°26° AprMay: average high 59 °F, low 33 °F 59°33° MayJune: average high 67 °F, low 41 °F 67°41° JunJuly: average high 69 °F, low 47 °F 69°47° JulAugust: average high 67 °F, low 44 °F 67°44° AugSeptember: average high 57 °F, low 37 °F 57°37° SepOctober: average high 44 °F, low 27 °F 44°27° OctNovember: average high 31 °F, low 17 °F 31°17° NovDecember: average high 27 °F, low 12 °F 27°12° Dec

Precipitation by month inches

0″2″4″6″January: 3.58 in precipitation 3.6 JanFebruary: 3.04 in precipitation 3.0 FebMarch: 2.17 in precipitation 2.2 MarApril: 1.70 in precipitation 1.7 AprMay: 1.33 in precipitation 1.3 MayJune: 1.03 in precipitation 1.0 JunJuly: 1.77 in precipitation 1.8 JulAugust: 3.23 in precipitation 3.2 AugSeptember: 5.97 in precipitation 6.0 SepOctober: 6.26 in precipitation 6.3 OctNovember: 4.94 in precipitation 4.9 NovDecember: 5.47 in precipitation 5.5 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Cooper Landing 5 W, AK (3 mi away); precipitation: Cooper Lake, AK (13 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

996315a
Moose Pass, AK · 12 mi
996055b
Hope, AK · 29 mi
996645b
Seward, AK · 31 mi
995115a
Anchorage, AK · 38 mi
995165b
Anchorage, AK · 39 mi
995405b
Indian, AK · 39 mi
995155a
Anchorage, AK · 41 mi
995075a
Anchorage, AK · 42 mi

Alaska planting zones →

Questions about 99572

What planting zone is ZIP code 99572?

ZIP code 99572 (Cooper Landing, AK) is in USDA hardiness zone 5a on the 2023 map: the coldest night of an average winter reaches −20 to −15 °F (−28.9 to −26.1 °C).

When is the last frost in Cooper Landing, AK?

The median last spring frost (32 °F) near 99572 is June 12; after July 2 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Cooper Landing 5 W station.

When is the first frost in Cooper Landing, AK?

The median first fall frost near 99572 is September 1, giving a median frost-free growing season of 78 days.

When should I plant tomatoes in 99572?

Start tomato seeds indoors around Apr 17 – May 1 and set transplants outside around Jun 19 – Jul 3, one to three weeks after the median last frost.

How much rain and snow does 99572 get?

About 40.5 inches of precipitation a year (NOAA 1991–2020 normals, Cooper Lake station).

How hot do summers get in Cooper Landing, AK?

The average high peaks at 69 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99572 have?

The USDA soil survey maps E23-boreal alpine scrub-gravelly colluvial slopes at the center of ZIP 99572: moderately decomposed plant material, well drained, pH about 5.0 (strongly acidic).

What kind of onions grow in Cooper Landing, AK?

Long-day onions: the longest day near 99572 is 19 h 05 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99572 change?

Yes. The 2012 USDA map put 99572 in zone 4b; the 2023 map puts it in zone 5a. The newer map uses 1991–2020 data and more weather stations.