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

Planting zone for 78538 — Edcouch, TX

ZIP code 78538 (Edcouch, Hidalgo County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 78538 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.

Zone10a30 to 35 °F

Coldest night−1.1 to 1.7 °C

Last frostrare

First frostrare

2012 zone9b

Was 9b 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 10a means →

Frost forecast — next 7 nights

live from the National Weather Service

Loading the forecast for Edcouch, 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

A 32 °F frost doesn't happen here in most winters. At the nearest station (NOAA station Santa Rosa 3 Wnw, TX — 9 miles away, elevation 49 ft) the median growing season is 355 days. When frost does come, it is a midwinter night or two; cover tender plants when a freeze is forecast.

Frost data: NOAA NCEI U.S. Climate Normals 1991–2020.

When spring arrived in 2026

In 2026, spring leaf-out near 78538 came on Jan 9 — 7 days earlier than the 1991–2020 average (Jan 16).

average
Jan 162026
Jan 9

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 10a in Texas

651 plants native to the lower 48 states, recorded in Texas, and rated by the USDA to survive 30 °F or colder — the bottom of zone 10a. 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 Edcouch, TX.

Soil in Edcouch, TX

The soil mapped at the center of ZIP 78538 is Willacy — fine sandy loam, well drained.

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

pH7.2neutral; most vegetables like 6.0–7.0

DrainageWell drainednatural drainage class

Organic matter2%moderate

Hydrologic groupBwater soaks in moderately

Farmland classprime farmlandUSDA classification

Map unit: Willacy fine sandy loam, 1 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 78538; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Edcouch, TX

Summer high97 °Faverage high, August

Winter low49 °Faverage low, January

Hot days166days a year at 90 °F or more

Freezing nights2nights a year at 32 °F or less

Growing degree days9,080base 50 °F — the season’s usable heat

Longest day13 h 48 mindaylight on June 21

Shortest day10 h 29 mindaylight on December 21

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

Precipitation24.6 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: Santa Rosa 3 Wnw, TX (9 mi away); precipitation: Santa Rosa 3 Wnw, TX (9 mi away). Daylight is calculated from latitude.

Nearby ZIP codes

1 of the 8 nearest ZIP codes are in a different zone — elevation and distance from water change winter lows quickly.

Sebastian, TX · 10 mi

Texas planting zones →

Questions about 78538

What planting zone is ZIP code 78538?

ZIP code 78538 (Edcouch, TX) is in USDA hardiness zone 10a on the 2023 map: the coldest night of an average winter reaches 30 to 35 °F (−1.1 to 1.7 °C).

How much rain and snow does 78538 get?

About 24.6 inches of precipitation a year (NOAA 1991–2020 normals, Santa Rosa 3 Wnw station).

How hot do summers get in Edcouch, TX?

The average high peaks at 97 °F in August, with about 166 days a year at 90 °F or more.

What kind of soil does 78538 have?

The USDA soil survey maps Willacy at the center of ZIP 78538: fine sandy loam, well drained, pH about 7.2 (neutral).

Did spring come early in Edcouch, TX in 2026?

Spring leaf-out near 78538 came on Jan 9 in 2026, 7 days earlier than the 1991–2020 average (Jan 16), according to the USA National Phenology Network Spring Index.

What kind of onions grow in Edcouch, TX?

Short-day onions: the longest day near 78538 is 13 h 48 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 78538 change?

Yes. The 2012 USDA map put 78538 in zone 9b; the 2023 map puts it in zone 10a. The newer map uses 1991–2020 data and more weather stations.