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

Planting zone for 99683 — Trapper Creek, AK

ZIP code 99683 (Trapper Creek, Matanuska-Susitna Borough) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is May 16 and the first fall frost September 16.

Where ZIP 99683 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 16

First frostSep 16

2012 zone4a

Was 4a 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 4b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Trapper Creek, 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 Trapper Creek, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostMay 16median — 50% chance of a later frost

Safe for tender plantsMay 28only 10% chance of frost after

First fall frostSeptember 16median — 10% chance by Sep 1

Growing season122 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 5 and returns around September 28.

From the NOAA station Talkeetna Airport, AK — 12 miles away, elevation 351 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 99683

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 4 – Apr 18

SpinachSow outdoors · Apr 4 – Apr 25

Broccoli, cabbageStart indoors · Mar 7 – Mar 21

Broccoli, cabbageTransplant · Apr 25 – May 9

Onion setsPlant outdoors · Apr 18 – May 2

PotatoesPlant outdoors · Apr 25 – May 9

LettuceSow outdoors · Apr 18 – May 2

Carrots, beetsSow outdoors · Apr 25 – May 9

TomatoesStart indoors · Mar 21 – Apr 4

TomatoesTransplant · May 23 – Jun 6

Peppers, eggplantStart indoors · Mar 7 – Mar 21

Peppers, eggplantTransplant · May 30 – Jun 13

BeansSow outdoors · May 23 – Jun 6

Sweet cornSow outdoors · May 23 – Jun 6

Cucumbers, squashSow outdoors · May 23 – Jun 6

Fall lettuce, spinachSow outdoors · Jul 22 – Aug 5

GarlicPlant cloves · Sep 2 – Oct 7

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 16) and first fall frost (Sep 16) 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 Trapper Creek, AK.

Soil in Trapper Creek, AK

The soil mapped at the center of ZIP 99683 is Nancy — 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 matter65%high

Hydrologic groupBwater soaks in moderately

Farmland classFarmland of local importanceUSDA classification

Map unit: Nancy-Kashwitna complex, 0 to 2 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 99683; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Trapper Creek, AK

Summer high69 °Faverage high, July

Winter low5 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights207nights a year at 32 °F or less

Growing degree days808base 50 °F — the season’s usable heat

Longest day19 h 58 mindaylight on June 21

Shortest day4 h 58 mindaylight on December 21

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

Precipitation26.5 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: Talkeetna Airport, AK (12 mi away); precipitation: Talkeetna Airport, AK (12 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.

996764b

Talkeetna, AK · 28 mi

Alaska planting zones →

Questions about 99683

What planting zone is ZIP code 99683?

ZIP code 99683 (Trapper Creek, 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 Trapper Creek, AK?

The median last spring frost (32 °F) near 99683 is May 16; after May 28 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Talkeetna Airport station.

When is the first frost in Trapper Creek, AK?

The median first fall frost near 99683 is September 16, giving a median frost-free growing season of 122 days.

When should I plant tomatoes in 99683?

Start tomato seeds indoors around Mar 21 – Apr 4 and set transplants outside around May 23 – Jun 6, one to three weeks after the median last frost.

How much rain and snow does 99683 get?

About 26.5 inches of precipitation a year (NOAA 1991–2020 normals, Talkeetna Airport station).

How hot do summers get in Trapper Creek, 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 99683 have?

The USDA soil survey maps Nancy at the center of ZIP 99683: moderately decomposed plant material, well drained, pH about 5.0 (strongly acidic).

What kind of onions grow in Trapper Creek, AK?

Long-day onions: the longest day near 99683 is 19 h 58 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99683 change?

Yes. The 2012 USDA map put 99683 in zone 4a; the 2023 map puts it in zone 4b. The newer map uses 1991–2020 data and more weather stations.