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

Planting zone for 99694 — Houston, AK

ZIP code 99694 (Houston, Matanuska-Susitna Borough) is in USDA zone 4a: the coldest winter night averages −30 to −25 °F. The median last spring frost is May 29 and the first fall frost September 7.

Where ZIP 99694 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 frostMay 29
First frostSep 7
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 Houston, 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 Houston, 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 9only 10% chance of frost after
First fall frostSeptember 7median — 10% chance by Aug 24
Growing season100 daysfrost-free, median

A hard freeze (28 °F) usually ends around May 14 and returns around September 19.

From the NOAA station Whites Crossing, AK — 8 miles away, elevation 269 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 99694

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 13 – Jul 27
GarlicPlant cloves · Aug 24 – Sep 28
Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (May 29) and first fall frost (Sep 7) 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 4a in Alaska

240 plants native to Alaska, recorded in Alaska, and rated by the USDA to survive −30 °F or colder — the bottom of zone 4a. Each links to its USDA PLANTS profile.

Trees 10

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 °FSitka spruce200 ft · blooms late spring · low shade tolerance · to −33 °F

Shrubs 42

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 °Fbog Labrador tea3 ft · blooms late spring · medium shade tolerance · to −33 °F

Wildflowers & perennials 102

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 78

Alaska oniongrass3 ft · blooms mid spring · low shade tolerance · to −33 °FAlpine Meadow-Foxtail0.5 ft · blooms mid spring · medium shade tolerance · to −33 °Falpine 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 °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 Houston, AK.

Soil in Houston, AK

The soil mapped at the center of ZIP 99694 is Kichatna — slightly decomposed plant material, well drained.

TextureSlightly decomposed plant materialtop layer
pH5.0strongly acidic; most vegetables like 6.0–7.0
DrainageWell drainednatural drainage class
Organic matter60%high
Hydrologic groupAwater soaks in fast
Farmland classNot prime farmlandUSDA classification

Map unit: Kichatna silt loam, 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 99694; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Houston, AK

Summer high71 °Faverage high, July
Winter low−2 °Faverage low, January
Hot days0days a year at 90 °F or more
Freezing nights228nights a year at 32 °F or less
Growing degree days794base 50 °F — the season’s usable heat
Longest day19 h 34 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
Snowfall62 inper year

Average high and low, by month

−10°0°10°20°30°40°50°60°70°80°32 °FJanuary: average high 16 °F, low -2 °F 16°−2° JanFebruary: average high 26 °F, low 2 °F 26°2° FebMarch: average high 34 °F, low 7 °F 34°7° MarApril: average high 48 °F, low 23 °F 48°23° AprMay: average high 61 °F, low 34 °F 61°34° MayJune: average high 69 °F, low 44 °F 69°44° JunJuly: average high 71 °F, low 49 °F 71°49° JulAugust: average high 67 °F, low 46 °F 67°46° AugSeptember: average high 57 °F, low 37 °F 57°37° SepOctober: average high 41 °F, low 24 °F 41°24° OctNovember: average high 23 °F, low 6 °F 23°6° NovDecember: average high 18 °F, low 0 °F 18°0° Dec

Precipitation by month inches · ❄ = snowfall

0″1″2″3″4″January: 0.73 in precipitation, 10.9 in snowfall 0.7❄11 JanFebruary: 0.87 in precipitation, 9 in snowfall 0.9❄9 FebMarch: 0.64 in precipitation, 8.7 in snowfall 0.6❄9 MarApril: 0.38 in precipitation, 2.3 in snowfall 0.4❄2 AprMay: 1.12 in precipitation, 0.3 in snowfall 1.1 MayJune: 1.75 in precipitation 1.8 JunJuly: 2.59 in precipitation 2.6 JulAugust: 3.44 in precipitation 3.4 AugSeptember: 2.86 in precipitation, 0.1 in snowfall 2.9 SepOctober: 1.84 in precipitation, 4.4 in snowfall 1.8❄4 OctNovember: 1.15 in precipitation, 11.3 in snowfall 1.1❄11 NovDecember: 1.46 in precipitation, 15 in snowfall 1.5❄15 Dec

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Whites Crossing, AK (8 mi away); precipitation: Anderson Lake, AK (16 mi away). 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.

996524a
Big Lake, AK · 9 mi
996234b
Wasilla, AK · 13 mi
996295a
Wasilla, AK · 13 mi
996875a
Wasilla, AK · 13 mi
996545a
Wasilla, AK · 13 mi
996883b
Willow, AK · 20 mi
995055a
Jber, AK · 24 mi
995065a
Jber, AK · 24 mi

Alaska planting zones →

Questions about 99694

What planting zone is ZIP code 99694?

ZIP code 99694 (Houston, 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).

When is the last frost in Houston, AK?

The median last spring frost (32 °F) near 99694 is May 29; after June 9 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Whites Crossing station.

When is the first frost in Houston, AK?

The median first fall frost near 99694 is September 7, giving a median frost-free growing season of 100 days.

When should I plant tomatoes in 99694?

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 99694 get?

About 18.8 inches of precipitation a year and 62 inches of snowfall (NOAA 1991–2020 normals, Anderson Lake station).

How hot do summers get in Houston, 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 99694 have?

The USDA soil survey maps Kichatna at the center of ZIP 99694: slightly decomposed plant material, well drained, pH about 5.0 (strongly acidic).

What kind of onions grow in Houston, AK?

Long-day onions: the longest day near 99694 is 19 h 34 min, so summer days reach 15+ hours, enough for long-day varieties (intermediate types work too).

Did the zone for 99694 change?

Yes. The 2012 USDA map put 99694 in zone 3b; the 2023 map puts it in zone 4a. The newer map uses 1991–2020 data and more weather stations.