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

Planting zone for 99756 — Manley Hot Springs, AK

ZIP code 99756 (Manley Hot Springs, Yukon-Koyukuk (CA) County) is in USDA zone 1b: the coldest winter night averages −55 to −50 °F. The median last spring frost is May 29 and the first fall frost August 28.

Where ZIP 99756 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.

Zone1b−55 to −50 °F
Coldest night−48.3 to −45.6 °C
Last frostMay 29
First frostAug 28
2012 zone1a

Was 1a 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 1b means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Manley Hot Springs, 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 Manley Hot Springs, AK

JanFebMarAprMayJunJulAugSepOctNovDec
Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free
Last spring frostMay 29median — 50% chance of a later frost
Safe for tender plantsJune 16only 10% chance of frost after
First fall frostAugust 28median — 10% chance by Aug 10
Growing season89 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 16 and returns around September 8.

From the NOAA station Tanana Calhoun Mem Airport, AK — 42 miles away, elevation 226 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 99756

JanFebMarAprMayJunJulAugSepOctNovDec
PeasSow outdoors · Apr 17 – May 1
SpinachSow outdoors · Apr 17 – May 8
Broccoli, cabbageStart indoors · Mar 20 – Apr 3
Broccoli, cabbageTransplant · May 8 – May 22
Onion setsPlant outdoors · May 1 – May 15
PotatoesPlant outdoors · May 8 – May 22
LettuceSow outdoors · May 1 – May 15
Carrots, beetsSow outdoors · May 8 – May 22
TomatoesStart indoors · Apr 3 – Apr 17
TomatoesTransplant · Jun 5 – Jun 19
Peppers, eggplantStart indoors · Mar 20 – Apr 3
Peppers, eggplantTransplant · Jun 12 – Jun 26
BeansSow outdoors · Jun 5 – Jun 19
Sweet cornSow outdoors · Jun 5 – Jun 19
Cucumbers, squashSow outdoors · Jun 5 – Jun 19
Fall lettuce, spinachSow outdoors · Jul 3 – Jul 17
GarlicPlant cloves · Aug 14 – Sep 18
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 29) and first fall frost (Aug 28) 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 1b in Alaska

37 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −55 °F or colder — the bottom of zone 1b. Each links to its USDA PLANTS profile.

Trees 7

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 °Ftamarack80 ft · blooms mid spring · high shade tolerance · to −79 °F

Shrubs 15

alpine bearberry0.5 ft · blooms early spring · medium shade tolerance · to −62 °Fhalberd willow3 ft · blooms early summer · to −62 °FLapland rosebay3 ft · blooms late spring · low shade tolerance · to −62 °Flingonberry0.5 ft · blooms summer · high shade tolerance · to −62 °Fmarsh Labrador tea0.5 ft · blooms summer · to −62 °Fnetleaf willow0.2 ft · blooms early summer · to −62 °F

Wildflowers & perennials 11

alpine sweetvetch2 ft · blooms early summer · high shade tolerance · to −62 °Farctic dock1 ft · blooms summer · high shade tolerance · to −62 °Farctic lupine2 ft · blooms spring · medium shade tolerance · to −62 °Farctic raspberry1 ft · blooms summer · high shade tolerance · to −62 °Feightpetal mountain-avens0.3 ft · blooms late spring · medium shade tolerance · to −62 °Fhigh northern buttercup1 ft · blooms summer · high shade tolerance · to −62 °F

Grasses 2

arctic bluegrass2 ft · high shade tolerance · to −62 °Flivid sedge1 ft · blooms early summer · high shade tolerance · to −62 °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 Manley Hot Springs, AK.

Soil in Manley Hot Springs, AK

The soil mapped at the center of ZIP 99756 is Iksgiza — slightly decomposed plant material, poorly drained.

TextureSlightly decomposed plant materialtop layer
pH5.0strongly acidic; most vegetables like 6.0–7.0
DrainagePoorly drainedconsider raised beds
Organic matter70%high
Hydrologic groupDwater soaks in very slowly
Farmland classNot prime farmlandUSDA classification

Map unit: Iksgiza peat, 0 to 3 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 99756; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Manley Hot Springs, AK

Summer high73 °Faverage high, June
Winter low−21 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights252nights a year at 32 °F or less
Growing degree days657base 50 °F — the season’s usable heat
Longest day21 h 41 mindaylight on June 21
Shortest day3 h 47 mindaylight on December 21
Onions to growLong-daysummer days reach 15+ hours, enough for long-day varieties (intermediate types work too)
Precipitation14 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 2 °F, low -21 °F 2°−21° JanFebruary: average high 12 °F, low -16 °F 12°−16° FebMarch: average high 24 °F, low -11 °F 24°−11° MarApril: average high 43 °F, low 13 °F 43°13° AprMay: average high 61 °F, low 30 °F 61°30° MayJune: average high 73 °F, low 40 °F 73°40° JunJuly: average high 72 °F, low 46 °F 72°46° JulAugust: average high 66 °F, low 41 °F 66°41° AugSeptember: average high 54 °F, low 29 °F 54°29° SepOctober: average high 33 °F, low 14 °F 33°14° OctNovember: average high 11 °F, low -10 °F 11°−10° NovDecember: average high 3 °F, low -15 °F 3°−15° Dec

Precipitation by month inches

0″1″2″3″January: 0.43 in precipitation 0.4 JanFebruary: 0.63 in precipitation 0.6 FebMarch: 0.50 in precipitation 0.5 MarApril: 0.58 in precipitation 0.6 AprMay: 0.91 in precipitation 0.9 MayJune: 1.90 in precipitation 1.9 JunJuly: 2.52 in precipitation 2.5 JulAugust: 2.29 in precipitation 2.3 AugSeptember: 1.65 in precipitation 1.6 SepOctober: 0.97 in precipitation 1.0 OctNovember: 1.04 in precipitation 1.0 NovDecember: 0.61 in precipitation 0.6 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Manley Hot Springs 15ne, AK (41 mi away); precipitation: Manley Hot Springs 15ne, AK (41 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

2 of the 4 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

997771b
Tanana, AK · 41 mi
997671b
Rampart, AK · 63 mi
997432a
Healy, AK · 65 mi
997572b
Lake Minchumina, AK · 73 mi

Alaska planting zones →

Questions about 99756

What planting zone is ZIP code 99756?

ZIP code 99756 (Manley Hot Springs, AK) is in USDA hardiness zone 1b on the 2023 map: the coldest night of an average winter reaches −55 to −50 °F (−48.3 to −45.6 °C).

When is the last frost in Manley Hot Springs, AK?

The median last spring frost (32 °F) near 99756 is May 29; after June 16 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Tanana Calhoun Mem Airport station.

When is the first frost in Manley Hot Springs, AK?

The median first fall frost near 99756 is August 28, giving a median frost-free growing season of 89 days.

When should I plant tomatoes in 99756?

Start tomato seeds indoors around Apr 3 – Apr 17 and set transplants outside around Jun 5 – Jun 19, one to three weeks after the median last frost.

How much rain and snow does 99756 get?

About 14 inches of precipitation a year (NOAA 1991–2020 normals, Manley Hot Springs 15ne station).

How hot do summers get in Manley Hot Springs, AK?

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

What kind of soil does 99756 have?

The USDA soil survey maps Iksgiza at the center of ZIP 99756: slightly decomposed plant material, poorly drained, pH about 5.0 (strongly acidic).

What kind of onions grow in Manley Hot Springs, AK?

Long-day onions: the longest day near 99756 is 21 h 41 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99756 change?

Yes. The 2012 USDA map put 99756 in zone 1a; the 2023 map puts it in zone 1b. The newer map uses 1991–2020 data and more weather stations.