textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1222 PM CDT Thu Sep 17 2026

- A Special Weather Statement is in effect for the inland Coastal Counties for elevated heat indices this afternoon.

- There is a low to moderate (20 to 40%) chance of showers and thunderstorms across Deep South Texas today and tomorrow.

- Moderate (level 2 of 4) to Major (level 3 of 4) Heat Risk will continue to remain a concern over the next week.

- Conditions should be drier for the weekend, but low to moderate rain chances return early next week.

DISCUSSION

Issued at 1222 PM CDT Thu Sep 17 2026

An unsettled weather pattern continues over the next few days as an area of strong high pressure over the Southeastern CONUS backbuilds westward, with northeasterly upper level flow beneath the underside of of this high reaching Deep South Texas. Because this northeasterly airmass has spent considerable time over the Gulf, the atmospheric profile is expected to remain deeply moist for the next few days, with PWATs increasing to over 2 inches. This will support low to moderate (20 to 40%) rain chances today and tomorrow. The rain is expected to be overall beneficial, with most areas receiving no more than half an inch. However, some heavier showers and thunderstorms could cause locally higher amounts with the potential for nuisance ponding.

As high pressure continues to build westward over northeastern Texas though the weekend, upper-level subsidence should help dry out conditions for the weekend. A shower or two cannot be ruled out along the sea breeze, but rain chances remain below 20% for both Saturday and Sunday. Rain chances are expected to pick up again next week as high pressure and subsidence weaken but with continued east-northeasterly moist upper-level flow. Sea breeze activity is possible each day next week (mostly east of I-69C), and some longer-range guidance hints at a pattern shift/potential shortwave disturbance later next week that could bring widespread low to moderate rain chances to all of Deep South Texas.

Heat Risk will remain a concern over the next week. Though increased cloud cover and rain chances may bring some small temperature relief by a few degrees, the humid airmass will continue to keep heat indices high. A Special Weather Statement is in effect today for the inland Coastal Counties, where Heat Indices could reach between 108-111 degrees this afternoon. Moderate (level 2 of 4) to Major (level 3 of 4) Heat Risk is expected to continue throughout the next week.

AVIATION

(18Z TAFS) Issued at 1222 PM CDT Thu Sep 17 2026

VFR conditions are expected at all airports with the potential for showers and thunderstorms this afternoon. Conditions could deteriorate in the vicinity of any showers and thunderstorms that happen to form near the airport. Winds are expected to be light to moderate and northeasterly.

MARINE

Issued at 1222 PM CDT Thu Sep 17 2026

Favorable conditions are expected over the next several days with light to moderate northeasterly winds and low to moderate (2 to 4 feet) wave heights. Offshore showers and thunderstorms are possible throughout the next week, which could temporarily deteriorate conditions in their immediate vicinity.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 80 95 78 95 / 40 40 10 20 HARLINGEN 76 97 74 98 / 30 30 10 20 MCALLEN 80 99 77 99 / 20 40 0 20 RIO GRANDE CITY 78 98 75 100 / 30 30 0 10 SOUTH PADRE ISLAND 81 89 81 88 / 40 30 10 10 BAYVIEW/PORT ISABEL 79 94 78 94 / 30 30 10 10

BRO WATCHES/WARNINGS/ADVISORIES

TX...None. GM...None.