textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1155 AM CDT Mon Aug 17 2026

- Hot, mainly dry, and at times breezy conditions will continue through next weekend.

- There is a 20-30% chance for an isolated to scattered shower or thunderstorm along the sea breeze today especially along and east of IH-69C/US-281; best timing between 11am-5pm CDT.

- Though no headlines are out at this time, fire weather concerns will remain on the table through next weekend.

- Generally favorable marine conditions are expected through next week with low to moderate winds and seas; Small Craft Exercise Caution (SCEC) conditions are possible over the Laguna Madre mid to late week.

DISCUSSION

Issued at 1155 AM CDT Mon Aug 17 2026

Hot, mainly rain-free, and at times breezy conditions will prevail through the forecast period or through next weekend across Deep South Texas and the Rio Grande Valley as a strong and broad 594-597 dam sub-tropical heat dome remains anchored overhead.

High temperatures during this time will range from the upper 90s to the mid 100s. Combine that with dewpoint temperatures in the 70s and heat indices will generally range between 105-115F degrees each day through next weekend. This will continue to result in widespread Moderate (Level 2 of 4) to Major (Level 3 of 4) Heat Risk through next weekend. Additional Special Weather Statements (SPSs) and maybe a Heat Advisory will be needed in the coming days across at least parts of the region with areas closer to the coast most favored due to higher humidity levels.

As of 11:50 AM CDT, the latest visible satellite imagery and radar data depicted a cumulus field over the eastern half of our CWA with isolated sprinkles/showers beginning to bubble up. Have decided to bump up PoPs slightly between 20-30% this morning/afternoon for areas near the coast to account for the potential for an isolated shower or thunderstorm this afternoon. The best timing for any showers or thunderstorms will be between the hours of 11am-5pm CDT with the greatest confidence being along and east of the IH-69C/US- 281 corridor.

The persistently hot and dry antecedent pattern with high evaporation rates and at times breezy conditions will aid in increased fire weather concerns through next weekend, particularly in the Tuesday through Friday time period as minimum relative humidity values get to near Fire Danger Statement (RFD) criteria. Even though, we do not have any fire weather headlines at this time, we urge that you continue to exercise fire weather safety measures.

AVIATION

(18Z TAFS) Issued at 1155 AM CDT Mon Aug 17 2026

Through 18z Tuesday....VFR conditions will prevail through the 18z TAF cycle.

Southeast winds 5-15 kts with isolated gusts as high as 20 kts will continue through this afternoon/evening before waning later this evening/tonight. Tonight, winds will trend towards light and variable to calm if not a slight component out of the southeast with wind speeds up to 5 kts. Winds will pick up in magnitude once again on Monday as mixing heights increase.

MARINE

Issued at 1155 AM CDT Mon Aug 17 2026

Generally favorable marine conditions are expected along the Lower Texas Coast through the next several days, with light to moderate winds and low to moderate seas in place. However, winds may increase over the Laguna Madre mid to late week, which could require Small Craft Should Exercise Caution at times.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 79 97 79 97 / 10 0 0 0 HARLINGEN 76 101 75 101 / 10 0 0 0 MCALLEN 79 103 79 103 / 10 0 0 0 RIO GRANDE CITY 78 103 76 103 / 10 0 0 0 SOUTH PADRE ISLAND 80 89 81 90 / 10 0 0 0 BAYVIEW/PORT ISABEL 78 96 78 96 / 10 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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