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

Planting zone for 99725 — Ester, AK

ZIP code 99725 (Ester, Fairbanks North Star County) is in USDA zone 3b: the coldest winter night averages −35 to −30 °F. The median last spring frost is May 24 and the first fall frost September 1.

Where ZIP 99725 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 frostMay 24
First frostSep 1
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 Ester, 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 Ester, 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 4only 10% chance of frost after
First fall frostSeptember 1median — 10% chance by Aug 19
Growing season98 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 13 and returns around September 11.

From the NOAA station Ester, AK — within 1 mile, elevation 656 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 99725

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 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 (May 24) 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 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.

Trees 8

balsam 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 °Fpaper birch70 ft · blooms mid spring · high shade tolerance · to −62 °Fquaking aspen65 ft · blooms mid spring · high shade tolerance · to −70 °Fsubalpine fir90 ft · blooms late spring · low shade tolerance · to −51 °F

Shrubs 32

alpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °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 °Fchokecherry25 ft · blooms mid spring · high shade tolerance · to −43 °F

Wildflowers & perennials 64

alkali buttercup1 ft · blooms late spring · low shade tolerance · to −38 °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 speedwell0.8 ft · blooms mid summer · low shade tolerance · to −38 °FAmerican vetch1.3 ft · blooms late spring · high shade tolerance · to −38 °F

Grasses 61

alpine 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 °Fbearded fescue1.2 ft · blooms late spring · low shade tolerance · to −38 °FBebb's sedge3 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 Ester, AK.

Soil in Ester, AK

The soil mapped at the center of ZIP 99725 is Steese — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer
pH6.1slightly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter90%high
Hydrologic groupBwater soaks in moderately
Farmland classFarmland of local importanceUSDA classification

Map unit: Steese silt loam, 3 to 7 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 99725; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Ester, AK

Summer high72 °Faverage high, July
Winter low−15 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights244nights a year at 32 °F or less
Growing degree days798base 50 °F — the season’s usable heat
Longest day21 h 52 mindaylight on June 21
Shortest day3 h 40 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation14.6 inper year, rain and melted snow

Average high and low, by month

−30°−20°−10°0°10°20°30°40°50°60°70°80°32 °FJanuary: average high 0 °F, low -15 °F 0°−15° JanFebruary: average high 11 °F, low -10 °F 11°−10° FebMarch: average high 25 °F, low -5 °F 25°−5° MarApril: average high 45 °F, low 18 °F 45°18° AprMay: average high 61 °F, low 34 °F 61°34° MayJune: average high 71 °F, low 45 °F 71°45° JunJuly: average high 72 °F, low 49 °F 72°49° JulAugust: average high 65 °F, low 43 °F 65°43° AugSeptember: average high 54 °F, low 31 °F 54°31° SepOctober: average high 33 °F, low 15 °F 33°15° OctNovember: average high 11 °F, low -5 °F 11°−5° NovDecember: average high 3 °F, low -12 °F 3°−12° Dec

Precipitation by month inches

0″1″2″3″January: 0.67 in precipitation 0.7 JanFebruary: 0.61 in precipitation 0.6 FebMarch: 0.53 in precipitation 0.5 MarApril: 0.41 in precipitation 0.4 AprMay: 0.68 in precipitation 0.7 MayJune: 2.08 in precipitation 2.1 JunJuly: 2.70 in precipitation 2.7 JulAugust: 2.83 in precipitation 2.8 AugSeptember: 1.51 in precipitation 1.5 SepOctober: 0.89 in precipitation 0.9 OctNovember: 0.89 in precipitation 0.9 NovDecember: 0.75 in precipitation 0.8 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Ester, AK (within 1 mile); precipitation: Ester, AK (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

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

997093b
Fairbanks, AK · 4 mi
997752b
Fairbanks, AK · 6 mi
997082a
Fairbanks, AK · 8 mi
997102b
Fairbanks, AK · 9 mi
997112a
Fairbanks, AK · 9 mi
997032a
Fort Wainwright, AK · 12 mi
997052a
North Pole, AK · 23 mi
997022a
Eielson Afb, AK · 32 mi

Alaska planting zones →

Questions about 99725

What planting zone is ZIP code 99725?

ZIP code 99725 (Ester, 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 Ester, AK?

The median last spring frost (32 °F) near 99725 is May 24; after June 4 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Ester station.

When is the first frost in Ester, AK?

The median first fall frost near 99725 is September 1, giving a median frost-free growing season of 98 days.

When should I plant tomatoes in 99725?

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 99725 get?

About 14.6 inches of precipitation a year (NOAA 1991–2020 normals, Ester station).

How hot do summers get in Ester, AK?

The average high peaks at 72 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99725 have?

The USDA soil survey maps Steese at the center of ZIP 99725: slightly decomposed plant material, well drained, pH about 6.1 (slightly acidic).

What kind of onions grow in Ester, AK?

Long-day onions: the longest day near 99725 is 21 h 52 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99725 change?

Yes. The 2012 USDA map put 99725 in zone 3a; the 2023 map puts it in zone 3b. The newer map uses 1991–2020 data and more weather stations.