textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1224 PM CDT Mon Sep 14 2026

- A Heat Advisory is in effect for the coastal counties through this evening. - Widespread extreme risks of heat-related illnesses (level 4/4) prevail on Monday, gradually improving from a major (level 3/4) and extreme risk on Tuesday and Wednesday to a mainly moderate (level 2/4) risk by Thursday.

- There is a 30-40% chance for showers and thunderstorms Thursday and Friday.

DISCUSSION

Issued at 1224 PM CDT Mon Sep 14 2026

Upper level high pressure over the southeastern US will continue to support broad subsidence aloft and triple digit high temperatures across Deep South Texas through Wednesday. Heat will continue to be a concern Tuesday and Wednesday afternoons, with heat index values ranging from 105-111 degrees. Additional Heat Advisories may be needed Tuesday or Wednesday afternoons.

Fire weather may be a concern Tuesday, as afternoon relative humidity values fall to 20-30% across most of the CWA as gusty winds increase through the afternoon. A brief Fire Danger Statement may be needed.

By Thursday, a shortwave rotating through the southern periphery of the upper-level high will likely increase forcing and mid level moisture across Deep South Texas through the later half of the week, leading to increased rain chances across the area Thursday and Friday.

AVIATION

(18Z TAFS) Issued at 1224 PM CDT Mon Sep 14 2026

VFR conditions are forecast to continue through the TAF period. Gusty southeasterly winds this afternoon are forecast to diminish this evening, with light southeasterly winds continuing overnight. Skies are generally forecast to remain mostly clear to partly cloudy.

MARINE

Issued at 1224 PM CDT Mon Sep 14 2026

Generally favorable marine conditions are forecast to continue through the period, with light to moderate southeasterly winds supporting slight to moderate seas. Isolated to scattered showers and thunderstorms will remain possible over the Gulf waters, with rain chances increasing Thursday and Friday.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 81 98 80 97 / 0 0 10 20 HARLINGEN 77 102 76 100 / 0 0 0 20 MCALLEN 81 104 80 103 / 0 0 0 10 RIO GRANDE CITY 79 105 78 103 / 0 0 0 10 SOUTH PADRE ISLAND 82 90 82 89 / 0 0 10 10 BAYVIEW/PORT ISABEL 79 97 78 95 / 0 0 10 10

BRO WATCHES/WARNINGS/ADVISORIES

TX...Heat Advisory until 6 PM CDT this evening for TXZ251-254-255-351- 354-355.

GM...None.