textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1043 PM CDT Wed Sep 16 2026

- A Special Weather Statement (SPS) is possible again across the counties along and/or east of US-281 on Thursday for heat indices of 108-111 F, generally occurring within the hours of 12 PM to 6 PM.

- Near daily low to medium chances of rain continue into the middle of next week, with the most widespread and highest chances (up to a 50-60% chance) on Thursday and Friday.

- Increased cloud cover should help maintain moderate to major risks of heat-related illnesses (levels 2/4 and 3/4).

- A low risk of life-threatening rip currents continues through Thursday afternoon.

DISCUSSION

Issued at 1043 PM CDT Wed Sep 16 2026

Aside from a more expansive area of triple digits possible this Sunday and next Monday, increased cloud coverage and daily low or low to medium chances of rain should limit most inland high temperatures to the upper 90s into the middle of next week, though lower 100s are still possible along/west of US-281, most widespread over Starr and Zapata counties. Dependent on the development of showers/thunderstorms and model guidance trends throughout tonight and Thursday morning, another SPS may issued by the oncoming shifts for the counties along and/or east of US-281 for heat indices of 108- 111 F Thursday afternoon into early Thursday evening.

Weather pattern-wise, easterly to northeasterly winds circulating about a surface high pressure spilling from the East Coast to the Gulf is progged to advect a plume of deep Gulf moisture, with PWATs measuring up to 2.0-2.4+ in., across deep south Texas beginning tonight and peaking during the day on Thursday; chances of rain increase near the coast late tonight to a low (15-30%) chance by Thursday morning, spreading westward and increasing along the seabreeze boundary to a low to medium (20-40%) along/west of US-281 by the afternoon/evening hours on Thursday, followed by a low to medium (20-40%) chance along/east of US-281 Thursday night and a low to medium (20-50%) chance across the region on Friday. In general, we currently expect that most areas will see anywhere from little or no rainfall to as much as around 0.20-0.30 of an inch in total Thursday into Friday. Nonetheless, given above average moisture content, heavy rain and localized minor flooding are possible within slower-moving or training of convection as well as frequent lightning and/or higher gusts within deeper thunderstorms. Additionally, increased cloud cover on Friday followed by drier air infiltrating the region on Saturday are anticipated to improve risks of heat-related illnesses from moderate to major on Thursday to mostly moderate with heat indices ranging around 103-109 F.

Subsidence associated with a high pressure aloft retreating back to the Southern Plains by Friday night cuts down on rain chances to a low (10-20%) chance along/east US-281 on Saturday and Sunday afternoon. Meanwhile, the high pressure begins to weaken, causing heights to lower throughout the weekend and into the middle of next week, allowing for moisture and divergence aloft associated with an upper level low spinning over the Gulf to gradually increase and expand chances of rain from a low (15-30%) on Monday a low to medium (20-40%) chance across most of the region by the middle of next week. Moderate to major heat risks return by Sunday and additional SPSs for heat indices of 108-111 F are possible.

AVIATION

(00Z TAFS) Issued at 558 PM CDT Wed Sep 16 2026

Moderate easterly winds this evening become light and/or variable tonight. Intermittent and scattered passing showers developing over KBRO tonight continue and spread to all terminals throughout the day tomorrow with isolated to scattered thunderstorms as moderate easterly winds return by the afternoon. Heavy rain is possible within any convection that develops, bringing the possibility of brief periods of MVFR conditions from reduced visibility, noted in the PROB30s tonight into tomorrow.

MARINE

Issued at 1043 PM CDT Wed Sep 16 2026

Gentle to moderate northeasterly to easterly winds continue and slight to moderate (2-4 ft) seas build to moderate (3-5 ft) by Thursday night. Gentle to moderate easterly to southeasterly winds and slight to moderate (1-3 ft) seas return over the weekend. Meanwhile, chances of rain increase late tonight to as much as a medium to high (40-70%) chance on Thursday, with low to medium chances continuing into Saturday and into next week.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 80 95 79 95 / 20 50 40 50 HARLINGEN 76 97 76 97 / 20 40 30 40 MCALLEN 80 99 80 98 / 10 40 30 50 RIO GRANDE CITY 78 100 78 98 / 0 30 20 40 SOUTH PADRE ISLAND 81 88 81 88 / 20 40 40 30 BAYVIEW/PORT ISABEL 78 94 78 94 / 20 40 30 40

BRO WATCHES/WARNINGS/ADVISORIES

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