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

Planting zone for 99666 — Nunam Iqua, AK

ZIP code 99666 (Nunam Iqua, Kusilvak County) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F.

Where ZIP 99666 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.

Zone4a−30 to −25 °F

Coldest night−34.4 to −31.7 °C

Last frostrare

First frostrare

2012 zone3b

Was 3b 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 4a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Nunam Iqua, 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

No NOAA station with frost records lies within 90 miles of Nunam Iqua, AK, so we don't show frost dates here rather than guess. Your local extension office can give you a date.

Soil in Nunam Iqua, AK

The soil mapped at the center of ZIP 99666 is E38-maritime wet meadow-silty low coastal plains — slightly decomposed plant material, very poorly drained.

TextureSlightly decomposed plant materialtop layer

pH5.3strongly acidic; most vegetables like 6.0–7.0

DrainageVery poorly drainedconsider raised beds

Organic matter80%high

Hydrologic groupB/Dmoderate when drained; wet otherwise

Farmland classNot prime farmlandUSDA classification

Map unit: Yukon-Kuskokwim Coastal Plain-Maritime Lowland-Coastal Plains, Low.

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 99666; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Nunam Iqua, AK

Longest day19 h 59 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)

Daylight is calculated from latitude.

Nearby ZIP codes

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

Scammon Bay, AK · 44 mi

996324a

Mountain Village, AK · 53 mi

Hooper Bay, AK · 72 mi

Alaska planting zones →

Questions about 99666

What planting zone is ZIP code 99666?

ZIP code 99666 (Nunam Iqua, AK) is in USDA hardiness zone 4a on the 2023 map: the coldest night of an average winter reaches −30 to −25 °F (−34.4 to −31.7 °C).

What kind of soil does 99666 have?

The USDA soil survey maps E38-maritime wet meadow-silty low coastal plains at the center of ZIP 99666: slightly decomposed plant material, very poorly drained, pH about 5.3 (strongly acidic).

What kind of onions grow in Nunam Iqua, AK?

Long-day onions: the longest day near 99666 is 19 h 59 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99666 change?

Yes. The 2012 USDA map put 99666 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.