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

Planting zone for 99745 — Hughes, AK

ZIP code 99745 (Hughes, 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 99745 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 zone2a

Was 2a on the 2012 map — half a zone colder 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 Hughes, 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 Hughes, 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 — 86 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 99745

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.

Soil in Hughes, AK

The soil mapped at the center of ZIP 99745 is E31-Boreal taiga-silty frozen loess slopes — peat, poorly drained.

TexturePeattop layer

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

DrainagePoorly drainedconsider raised beds

Organic matter80%high

Hydrologic groupDwater soaks in very slowly

Farmland classNot prime farmlandUSDA classification

Map unit: Interior Alaska Highlands-Boreal Upland-Hills and Plains.

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 99745; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Hughes, AK

Summer high71 °Faverage high, July

Winter low−17 °Faverage low, January

Hot days0days a year at 90 °F or more

Freezing nights236nights a year at 32 °F or less

Growing degree days742base 50 °F — the season’s usable heat

Longest day24 h 00 mindaylight on June 21

Shortest day2 h 43 mindaylight on December 21

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

Average high and low, by month

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Tanana Calhoun Mem Airport, AK (86 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

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

997201a

Allakaket, AK · 54 mi

997683a

Ruby, AK · 58 mi

Alaska planting zones →

Questions about 99745

What planting zone is ZIP code 99745?

ZIP code 99745 (Hughes, 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 Hughes, AK?

The median last spring frost (32 °F) near 99745 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 Hughes, AK?

The median first fall frost near 99745 is August 28, giving a median frost-free growing season of 89 days.

When should I plant tomatoes in 99745?

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 hot do summers get in Hughes, AK?

The average high peaks at 71 °F in July, with about 0 days a year at 90 °F or more.

What kind of soil does 99745 have?

The USDA soil survey maps E31-Boreal taiga-silty frozen loess slopes at the center of ZIP 99745: peat, poorly drained, pH about 4.8 (strongly acidic).

What kind of onions grow in Hughes, AK?

Long-day onions: the longest day near 99745 is 24 h 00 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99745 change?

Yes. The 2012 USDA map put 99745 in zone 2a; the 2023 map puts it in zone 1b. The newer map uses 1991–2020 data and more weather stations.