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

Planting zone for 99743 — Healy, AK

ZIP code 99743 (Healy, Denali County) is in USDA zone 2a: the coldest winter night averages −50 to −45 °F. The median last spring frost is May 24 and the first fall frost September 2.

Where ZIP 99743 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.

Zone2a−50 to −45 °F

Coldest night−45.6 to −42.8 °C

Last frostMay 24

First frostSep 2

2012 zone3a

Was 3a on the 2012 map — a full zone colder now. The zone is the one at the center of the ZIP code; hilly ZIPs can span two zones. What zone 2a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Healy, 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 Healy, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 24median — 50% chance of a later frost

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

First fall frostSeptember 2median — 10% chance by Aug 17

Growing season100 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 12 and returns around September 13.

From the NOAA station Kobe Hill, AK — 25 miles away, elevation 801 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 99743

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 12 – Apr 26

SpinachSow outdoors · Apr 12 – May 3

Broccoli, cabbageStart indoors · Mar 15 – Mar 29

Broccoli, cabbageTransplant · May 3 – May 17

Onion setsPlant outdoors · Apr 26 – May 10

PotatoesPlant outdoors · May 3 – May 17

LettuceSow outdoors · Apr 26 – May 10

Carrots, beetsSow outdoors · May 3 – May 17

TomatoesStart indoors · Mar 29 – Apr 12

TomatoesTransplant · May 31 – Jun 14

Peppers, eggplantStart indoors · Mar 15 – Mar 29

Peppers, eggplantTransplant · Jun 7 – Jun 21

BeansSow outdoors · May 31 – Jun 14

Sweet cornSow outdoors · May 31 – Jun 14

Cucumbers, squashSow outdoors · May 31 – Jun 14

Fall lettuce, spinachSow outdoors · Jul 8 – Jul 22

GarlicPlant cloves · Aug 19 – Sep 23

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 24) and first fall frost (Sep 2) 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 2a in Alaska

44 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −50 °F or colder — the bottom of zone 2a. 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 Healy, AK.

Soil in Healy, AK

The soil mapped at the center of ZIP 99743 is Boreal-taiga high elevation silty loess slopes — peat, poorly drained.

TexturePeattop layer

pH4.8strongly acidic; most vegetables like 6.0–7.0

DrainagePoorly drainedconsider raised beds

Organic matter75%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Boreal Plateaus with Continuous Permafrost.

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 99743; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Healy, AK

Summer high73 °Faverage high, July

Winter low−13 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights235nights a year at 32 °F or less

Growing degree days922base 50 °F — the season’s usable heat

Longest day20 h 58 mindaylight on June 21

Shortest day4 h 14 mindaylight on December 21

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

Precipitation16.3 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: Kobe Hill, AK (25 mi away); precipitation: Kobe Hill, AK (25 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.

997553b

Denali National Park, AK · 26 mi

Manley Hot Springs, AK · 65 mi

997582a

Minto, AK · 87 mi

996764b

Talkeetna, AK · 94 mi

996834b

Trapper Creek, AK · 105 mi

Alaska planting zones →

Questions about 99743

What planting zone is ZIP code 99743?

ZIP code 99743 (Healy, AK) is in USDA hardiness zone 2a on the 2023 map: the coldest night of an average winter reaches −50 to −45 °F (−45.6 to −42.8 °C).

When is the last frost in Healy, AK?

The median last spring frost (32 °F) near 99743 is May 24; after June 10 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Kobe Hill station.

When is the first frost in Healy, AK?

The median first fall frost near 99743 is September 2, giving a median frost-free growing season of 100 days.

When should I plant tomatoes in 99743?

Start tomato seeds indoors around Mar 29 – Apr 12 and set transplants outside around May 31 – Jun 14, one to three weeks after the median last frost.

How much rain and snow does 99743 get?

About 16.3 inches of precipitation a year (NOAA 1991–2020 normals, Kobe Hill station).

How hot do summers get in Healy, AK?

The average high peaks at 73 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99743 have?

The USDA soil survey maps Boreal-taiga high elevation silty loess slopes at the center of ZIP 99743: peat, poorly drained, pH about 4.8 (strongly acidic).

What kind of onions grow in Healy, AK?

Long-day onions: the longest day near 99743 is 20 h 58 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99743 change?

Yes. The 2012 USDA map put 99743 in zone 3a; the 2023 map puts it in zone 2a. The newer map uses 1991–2020 data and more weather stations.