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

Planting zone for 77412 — Altair, TX

ZIP code 77412 (Altair, Colorado County) is in USDA zone 9a: the coldest winter night averages 20 to 25 °F. The median last spring frost is February 21 and the first fall frost December 1.

Where ZIP 77412 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.

Zone9a20 to 25 °F

Coldest night−6.7 to −3.9 °C

Last frostFeb 21

First frostDec 1

2012 zone8b

Was 8b 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 9a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Altair, TX…

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 Altair, TX

JanFebMarAprMayJunJulAugSepOctNovDec

Blue: frost possible · fading green: frost risk falling or rising (90% → 10%) · green: frost-free

Last spring frostFebruary 21median — 50% chance of a later frost

Safe for tender plantsMarch 14only 10% chance of frost after

First fall frostDecember 1median — 10% chance by Nov 10

Growing season285 daysfrost-free, median

A hard freeze (28 °F) usually ends around January 30 and returns around December 18.

From the NOAA station Eagle Lake Resch Center, TX — 7 miles away, elevation 177 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 77412

JanFebMarAprMayJunJulAugSepOctNovDec

PeasSow outdoors · Jan 10 – Jan 24

SpinachSow outdoors · Jan 10 – Jan 31

Broccoli, cabbageStart indoors · Dec 13 – Dec 27

Broccoli, cabbageTransplant · Jan 31 – Feb 14

Onion setsPlant outdoors · Jan 24 – Feb 7

PotatoesPlant outdoors · Jan 31 – Feb 14

LettuceSow outdoors · Jan 24 – Feb 7

Carrots, beetsSow outdoors · Jan 31 – Feb 14

TomatoesStart indoors · Dec 27 – Jan 10

TomatoesTransplant · Feb 28 – Mar 14

Peppers, eggplantStart indoors · Dec 13 – Dec 27

Peppers, eggplantTransplant · Mar 7 – Mar 21

BeansSow outdoors · Feb 28 – Mar 14

Sweet cornSow outdoors · Feb 28 – Mar 14

Cucumbers, squashSow outdoors · Feb 28 – Mar 14

Fall lettuce, spinachSow outdoors · Oct 6 – Oct 20

GarlicPlant cloves · Nov 17 – Dec 22

Start seeds indoorsSow or plant outdoorsFall plantingMedian last & first frost

Counted from the median last spring frost (Feb 21) and first fall frost (Dec 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.

When spring arrived in 2026

In 2026, spring leaf-out near 77412 came on Jan 15 — 9 days earlier than the 1991–2020 average (Jan 24).

average
Jan 242026
Jan 15

JanFebMarAprMayJun

The Spring Index marks the day when accumulated warmth is enough for lilac and honeysuckle to leaf out — a widely used signal that the growing season has started. Source: USA National Phenology Network, www.usanpn.org — Spring Indices, first leaf, 2026 (data as of 2026-09-08) and 30-year average 1991–2020 (CC BY 4.0).

Native plants for zone 9a in Texas

640 plants native to the lower 48 states, recorded in Texas, and rated by the USDA to survive 20 °F or colder — the bottom of zone 9a. Each links to its USDA PLANTS profile.

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 Altair, TX.

Soil in Altair, TX

The soil mapped at the center of ZIP 77412 is Telf — fine sandy loam, moderately well drained.

TextureFine sandy loamdrains and warms fast; dries out and needs more feeding

pH5.9moderately acidic; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter0.93%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classFarmland of statewide importanceUSDA classification

Map unit: Telf fine sandy loam, 0 to 1 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 77412; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Altair, TX

Summer high96 °Faverage high, August

Winter low40 °Faverage low, January

Hot days116days a year at 90 °F or more

Freezing nights14nights a year at 32 °F or less

Growing degree days7,251base 50 °F — the season’s usable heat

Longest day14 h 03 mindaylight on June 21

Shortest day10 h 15 mindaylight on December 21

Onions to growShort-daysummer days stay under about 14 h 20 min, so long-day varieties won’t bulb

Precipitation46.9 inper year, rain and melted snow

Average high and low, by month

Precipitation by month inches

NOAA NCEI U.S. Climate Normals 1991–2020 — temperature: Eagle Lake Resch Center, TX (7 mi away); precipitation: Eagle Lake Resch Center, TX (7 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 9a.

774709a

Rock Island, TX · 5 mi

774429a

Garwood, TX · 9 mi

774349a

Eagle Lake, TX · 9 mi

Texas planting zones →

Questions about 77412

What planting zone is ZIP code 77412?

ZIP code 77412 (Altair, TX) is in USDA hardiness zone 9a on the 2023 map: the coldest night of an average winter reaches 20 to 25 °F (−6.7 to −3.9 °C).

When is the last frost in Altair, TX?

The median last spring frost (32 °F) near 77412 is February 21; after March 14 there is only a 10% chance of frost. Data: NOAA 1991–2020 normals, Eagle Lake Resch Center station.

When is the first frost in Altair, TX?

The median first fall frost near 77412 is December 1, giving a median frost-free growing season of 285 days.

When should I plant tomatoes in 77412?

Start tomato seeds indoors around Dec 27 – Jan 10 and set transplants outside around Feb 28 – Mar 14, one to three weeks after the median last frost.

How much rain and snow does 77412 get?

About 46.9 inches of precipitation a year (NOAA 1991–2020 normals, Eagle Lake Resch Center station).

How hot do summers get in Altair, TX?

The average high peaks at 96 °F in August, with about 116 days a year at 90 °F or more.

What kind of soil does 77412 have?

The USDA soil survey maps Telf at the center of ZIP 77412: fine sandy loam, moderately well drained, pH about 5.9 (moderately acidic).

Did spring come early in Altair, TX in 2026?

Spring leaf-out near 77412 came on Jan 15 in 2026, 9 days earlier than the 1991–2020 average (Jan 24), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Altair, TX?

Short-day onions: the longest day near 77412 is 14 h 03 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 77412 change?

Yes. The 2012 USDA map put 77412 in zone 8b; the 2023 map puts it in zone 9a. The newer map uses 1991–2020 data and more weather stations.