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

Planting zone for 99674 — Sutton, AK

ZIP code 99674 (Sutton, Matanuska-Susitna Borough) is in USDA zone 4b: the coldest winter night averages −25 to −20 °F. The median last spring frost is June 1 and the first fall frost September 6.

Where ZIP 99674 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 frostJun 1

First frostSep 6

2012 zone4b

Same zone as on the 2012 map. 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 Sutton, 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 Sutton, AK

JanFebMarAprMayJunJulAugSepOctNovDec

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

Last spring frostJune 1median — 50% chance of a later frost

Safe for tender plantsJune 13only 10% chance of frost after

First fall frostSeptember 6median — 10% chance by Aug 24

Growing season98 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 18 and returns around September 21.

From the NOAA station Sutton 1 W, AK — 29 miles away, elevation 551 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 99674

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Apr 20 – May 4

SpinachSow outdoors · Apr 20 – May 11

Broccoli, cabbageStart indoors · Mar 23 – Apr 6

Broccoli, cabbageTransplant · May 11 – May 25

Onion setsPlant outdoors · May 4 – May 18

PotatoesPlant outdoors · May 11 – May 25

LettuceSow outdoors · May 4 – May 18

Carrots, beetsSow outdoors · May 11 – May 25

TomatoesStart indoors · Apr 6 – Apr 20

TomatoesTransplant · Jun 8 – Jun 22

Peppers, eggplantStart indoors · Mar 23 – Apr 6

Peppers, eggplantTransplant · Jun 15 – Jun 29

BeansSow outdoors · Jun 8 – Jun 22

Sweet cornSow outdoors · Jun 8 – Jun 22

Cucumbers, squashSow outdoors · Jun 8 – Jun 22

Fall lettuce, spinachSow outdoors · Jul 12 – Jul 26

GarlicPlant cloves · Aug 23 – Sep 27

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Jun 1) and first fall frost (Sep 6) 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 Sutton, AK.

Soil in Sutton, AK

The soil mapped at the center of ZIP 99674 is E28-boreal alpine dwarf scrub-gravelly colluvial slopes — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer

DrainageWell drainednatural drainage class

Organic matter75%high

Hydrologic groupBwater soaks in moderately

Farmland classNot prime farmlandUSDA classification

Map unit: Interior Alaska Mountains-Boreal Alpine-Barren 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 99674; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Sutton, AK

Summer high69 °Faverage high, July

Winter low9 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights227nights a year at 32 °F or less

Growing degree days611base 50 °F — the season’s usable heat

Longest day19 h 33 mindaylight on June 21

Shortest day5 h 18 mindaylight on December 21

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

Precipitation18.8 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: Sutton 1 W, AK (29 mi away); precipitation: Sutton 1 W, AK (29 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

Eagle River, AK · 50 mi

995875b

Girdwood, AK · 51 mi

Alaska planting zones →

Questions about 99674

What planting zone is ZIP code 99674?

ZIP code 99674 (Sutton, 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 Sutton, AK?

The median last spring frost (32 °F) near 99674 is June 1; after June 13 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Sutton 1 W station.

When is the first frost in Sutton, AK?

The median first fall frost near 99674 is September 6, giving a median frost-free growing season of 98 days.

When should I plant tomatoes in 99674?

Start tomato seeds indoors around Apr 6 – Apr 20 and set transplants outside around Jun 8 – Jun 22, one to three weeks after the median last frost.

How much rain and snow does 99674 get?

About 18.8 inches of precipitation a year (NOAA 1991–2020 normals, Sutton 1 W station).

How hot do summers get in Sutton, 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 99674 have?

The USDA soil survey maps E28-boreal alpine dwarf scrub-gravelly colluvial slopes at the center of ZIP 99674: slightly decomposed plant material, well drained.

What kind of onions grow in Sutton, AK?

Long-day onions: the longest day near 99674 is 19 h 33 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).