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

Planting zone for 78503 — Mcallen, TX

ZIP code 78503 (Mcallen, Hidalgo County) is in USDA zone 10a: the coldest winter night averages 30 to 35 °F.

Where ZIP 78503 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 Mcallen, 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 Mcallen Miller Intl Airport, TX — within 1 mile, elevation 102 ft) the median growing season is 365 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 78503 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 Mcallen, TX.

Soil in Mcallen, TX

The soil mapped at the center of ZIP 78503 is Runn — silty clay, moderately well drained.

TextureSilty clayholds water and nutrients; slow to drain and warm up

pH8.2alkaline; most vegetables like 6.0–7.0

DrainageModerately well drainednatural drainage class

Organic matter0.75%low — add compost

Hydrologic groupCwater soaks in slowly

Farmland classprime farmlandUSDA classification

Map unit: Runn silty clay.

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 78503; soils change within a few hundred feet, so a home soil test (pH, nutrients) is still the best guide.

Climate in Mcallen, TX

Summer high100 °Faverage high, August

Winter low53 °Faverage low, January

Hot days177days a year at 90 °F or more

Freezing nights1nights a year at 32 °F or less

Growing degree days10,039base 50 °F — the season’s usable heat

Longest day13 h 47 mindaylight on June 21

Shortest day10 h 30 mindaylight on December 21

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

Precipitation22.2 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: Mcallen Miller Intl Airport, TX (within 1 mile); precipitation: Mcallen Miller Intl Airport, TX (within 1 mile). Daylight is calculated from latitude.

Nearby ZIP codes

All 8 nearest ZIP codes share zone 10a.

All 5 ZIP codes in Mcallen → · Texas planting zones →

Questions about 78503

What planting zone is ZIP code 78503?

ZIP code 78503 (Mcallen, 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 78503 get?

About 22.2 inches of precipitation a year (NOAA 1991–2020 normals, Mcallen Miller Intl Airport station).

How hot do summers get in Mcallen, TX?

The average high peaks at 100 °F in August, with about 177 days a year at 90 °F or more.

What kind of soil does 78503 have?

The USDA soil survey maps Runn at the center of ZIP 78503: silty clay, moderately well drained, pH about 8.2 (alkaline).

Did spring come early in Mcallen, TX in 2026?

Spring leaf-out near 78503 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 Mcallen, TX?

Short-day onions: the longest day near 78503 is 13 h 47 min, so summer days stay under about 14 h 20 min, so long-day varieties won’t bulb.

Did the zone for 78503 change?

Yes. The 2012 USDA map put 78503 in zone 9b; the 2023 map puts it in zone 10a. The newer map uses 1991–2020 data and more weather stations.