textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1143 AM CDT Sun Aug 9 2026

- Showers and thunderstorms along the sea breeze will take place this afternoon into this evening; current probabilities range between 30-40%.

- Hot and dry conditions return to the region Monday and will persist through next week. - High temperatures in the upper 90s to mid 100s with heat indices between 105-115F degrees will result in widespread Major (Level 3 of 4) with pockets of Extreme (Level 4 of 4) Heat Risk next week.

- Special Weather Statements (SPSs) and Heat Advisories are possible next week given the return of the heat.

- Becoming breezy at times next week with southeast winds 15-25 mph gusting 30-40 mph.

- Favorable marine conditions will persist into the early parts of the week before becoming more unfavorable mid to late week amid increased winds.

DISCUSSION

Issued at 1143 AM CDT Sun Aug 9 2026

Sea breeze convection developing later this afternoon/evening is the primary weather concern in the near term. Several CAM and AI/ML models continue to signal the increased potential for showers and thunderstorms developing along the sea breeze later this afternoon. Activity is expected to be more robust than yesterday in both coverage and intensity. We've bumped up PoPs and adjusted the wx grids this morning in anticipation for showers and thunderstorms later on.

Currently, the latest radar and satellite data reveals most of the coverage over the open Gulf Waters. Showers and thunderstorms will start off along/near the coast later this afternoon before spreading westward as the afternoon progress. Given the elevated atmospheric moisture content (high PWAT values), CAPE values between 2,000-4,000 J/kg, and increased heating, the atmosphere will be favorable for this kind of activity later on today. Any showers or storms that develop will have the capabilities of producing heavy downpours, lightning, and brief gusty winds.

Increased cloud coverage and rain chances will keep the heat in check today as high temperatures will at seasonable levels. High temperatures are expected to top out in the mid 90s near the coast to near 100F degrees well inland west of IH-69C/US-281.

The heat and dry theme returns Monday and will persist through next week as mid-upper ridging re-establishes itself and strengthens over the region. Highs are progged to return to hotter than normal levels with values ranging from the upper 90s to mid 100s. Peak heat indices between 105-115F degrees will result in increased heat risk during the week. Widespread Major (Level 3 of 4) with pockets of Extreme (Level 4 of 4) will be common through much of next week. Special Weather Statements (SPS) and Heat Advisories may be needed at times next week.

It will also be breezy next week with southeast winds 15-30 mph gusting up to 40 mph.

AVIATION

(18Z TAFS) Issued at 1143 AM CDT Sun Aug 9 2026

Through 18z Monday.....Scattered showers and thunderstorms along the seabreeze this afternoon into this evening is the primary weather concern during the 18z TAF period. As of 11:20 AM CDT, GOES-East Visible Satellite imagery and observations depicted a growing linear and westward advancing cumulus field (associated with the sea breeze) near the coast including over KHRL and KBRO. VFR conditions were taking place as well under a SCT-BKN deck of cumulus clouds with ceilings ranging between 30,000-50,000 feet AGL and unrestricted visibilities.

Over the next few hours, initiation of showers and thunderstorms will begin taking place over the area with the greatest probabilities and coverage over the coastal counties. The best timing for showers and thunderstorms will be between 16-22z/Sun. Current probabilities of showers and storms range between 30-40% this afternoon. Have introduced TEMPO groups for KBRO, KHRL, and KMFE to take into account the likelihood of showers and thunderstorms. Any showers or storms that develop or pass over a TAF site will have the capabilities or producing heavy downpours restricting visibilities, lightning, and gusty winds. Flight categories being reduced to MVFR/IFR levels are possible with any shower or thunderstorm.

Sea breeze convection will decrease in coverage as they advance westward and/or dissipate with the loss of daytime heating. This will give way to a return to VFR conditions late this evening which will persist through the overnight hours. There could be a few MVFR clouds that develop late tonight due to the copious amounts of low level moisture.

Winds will continue out of the southeast 5-12 kts through the forecast period.

MARINE

Issued at 1143 AM CDT Sun Aug 9 2026

Generally favorable marine conditions will persist into the beginning parts of the workweek with low to moderate winds and seas. However, slightly stronger winds could result in more adverse marine conditions mid to late week. Small Craft Exercise Caution (SCEC) conditions is possible mid to late week along the Laguna Madre especially and maybe portions of the Gulf. A brief period of Small Craft Advisory conditions could develop over the Laguna Madre mid to late week.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 80 96 81 96 / 10 10 0 0 HARLINGEN 76 98 77 99 / 10 10 0 0 MCALLEN 80 101 80 103 / 20 0 0 0 RIO GRANDE CITY 78 101 78 103 / 10 0 0 0 SOUTH PADRE ISLAND 81 89 81 89 / 10 10 0 0 BAYVIEW/PORT ISABEL 79 95 79 96 / 10 10 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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