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

Planting zone for 99755 — Denali National Park, AK

ZIP code 99755 (Denali National Park, Denali County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is June 6 and the first fall frost August 25.

Where ZIP 99755 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.

Zone3b−35 to −30 °F

Coldest night−37.2 to −34.4 °C

Last frostJun 6

First frostAug 25

2012 zone3a

Was 3a 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 3b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Denali National Park, 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 Denali National Park, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 6median — 50% chance of a later frost

Safe for tender plantsJune 30only 10% chance of frost after

First fall frostAugust 25median — 10% chance by Aug 9

Growing season77 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 21 and returns around September 6.

From the NOAA station Mckinley Park, AK — 8 miles away, elevation 2,070 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 99755

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 25 – May 9

SpinachSow outdoors · Apr 25 – May 16

Broccoli, cabbageStart indoors · Mar 28 – Apr 11

Broccoli, cabbageTransplant · May 16 – May 30

Onion setsPlant outdoors · May 9 – May 23

PotatoesPlant outdoors · May 16 – May 30

LettuceSow outdoors · May 9 – May 23

Carrots, beetsSow outdoors · May 16 – May 30

TomatoesStart indoors · Apr 11 – Apr 25

TomatoesTransplant · Jun 13 – Jun 27

Peppers, eggplantStart indoors · Mar 28 – Apr 11

Peppers, eggplantTransplant · Jun 20 – Jul 4

BeansSow outdoors · Jun 13 – Jun 27

Sweet cornSow outdoors · Jun 13 – Jun 27

Cucumbers, squashSow outdoors · Jun 13 – Jun 27

Fall lettuce, spinachSow outdoors · Jun 30 – Jul 14

GarlicPlant cloves · Aug 11 – Sep 15

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 6) and first fall frost (Aug 25) 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 3b in Alaska

172 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −35 °F or colder — the bottom of zone 3b. 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 Denali National Park, AK.

Soil in Denali National Park, AK

The soil mapped at the center of ZIP 99755 is Alpine-dwarf scrub gravelly colluvial slopes — 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 matter75%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Nonvegetated Mountains, Alaska 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 99755; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Denali National Park, AK

Summer high66 °Faverage high, July

Winter low−6 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights242nights a year at 32 °F or less

Growing degree days414base 50 °F — the season’s usable heat

Longest day20 h 50 mindaylight on June 21

Shortest day4 h 20 mindaylight on December 21

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

Precipitation15.9 inper year, rain and melted snow

Snowfall77 inper year; 206 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: Mckinley Park, AK (8 mi away); precipitation: Mckinley Park, AK (8 mi away). 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.

Talkeetna, AK · 83 mi

997093b

Fairbanks, AK · 84 mi

997253b

Ester, AK · 84 mi

Alaska planting zones →

Questions about 99755

What planting zone is ZIP code 99755?

ZIP code 99755 (Denali National Park, AK) is in USDA hardiness zone 3b on the 2023 map: the coldest night of an average winter reaches −35 to −30 °F (−37.2 to −34.4 °C).

When is the last frost in Denali National Park, AK?

The median last spring frost (32 °F) near 99755 is June 6; after June 30 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Mckinley Park station.

When is the first frost in Denali National Park, AK?

The median first fall frost near 99755 is August 25, giving a median frost-free growing season of 77 days.

When should I plant tomatoes in 99755?

Start tomato seeds indoors around Apr 11 – Apr 25 and set transplants outside around Jun 13 – Jun 27, one to three weeks after the median last frost.

How much rain and snow does 99755 get?

About 15.9 inches of precipitation a year and 77 inches of snowfall (NOAA 1991–2020 normals, Mckinley Park station).

How hot do summers get in Denali National Park, AK?

The average high peaks at 66 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99755 have?

The USDA soil survey maps Alpine-dwarf scrub gravelly colluvial slopes at the center of ZIP 99755: slightly decomposed plant material, well drained, pH about 4.7 (strongly acidic).

What kind of onions grow in Denali National Park, AK?

Long-day onions: the longest day near 99755 is 20 h 50 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99755 change?

Yes. The 2012 USDA map put 99755 in zone 3a; the 2023 map puts it in zone 3b. The newer map uses 1991–2020 data and more weather stations.