textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 130 PM CDT Fri Sep 4 2026

- Major (level 3 of 4) to Extreme (level 4 of 4) Heat Risk is expected throughout much of Deep South Texas through early next week.

- A combination low afternoon relative humidity, dry grasses, and hot temperatures may raise concerns for favorable fire weather through Friday.

- Sea breeze showers and thunderstorms along and east of I-69C are possible each afternoon Labor Day Weekend and continuing into early next week.

DISCUSSION

Issued at 130 PM CDT Fri Sep 4 2026

Triple-digit heat will continue to be the main weather concern across Deep South Texas through Labor Day weekend, but some relief from the heat is expected for portions of the region as low rain/storm chances return. The combination of unseasonably hot temperatures and elevated humidity will result in heat indices ranging from 106-110 degrees, although a few areas may briefly reach 111-113 degrees each afternoon. Historical data for Labor Day indicates the probability of a high temperature of at least 100 degrees is 1% for Brownsville International Airport, 8% for Harlingen International Airport, and 21% for McAllen International Airport. While these odds are promising, it will still be hot with temperatures expected to run around 5-7 degrees above normal through Labor Day. If spending time outdoors, continue to practice heat safety to prevent heat related illnesses.

Low rain/storm chances (around 20-30%) return this weekend and on Labor Day, mainly along and east of US-281. Precipitable water values are expected to increase this weekend as weak mid level energy translates along the periphery of ridging aloft. This should result in a sightly more active sea breeze, mainly during the late morning and early evening hours as the boundary pushes inland. Taking a look at some Labor Day climatology statistics, the chance of receiving at greater than or equal to 0.01 inches of rain on Labor Day is 33% for Brownsville International Airport, 45% for Harlingen International Airport, and 25% for McAllen International Airport. Model guidance continues to trend towards slightly better rain chances (20-40%) for next Tuesday through Thursday, although overall rainfall amounts look to be fairly light. Well take what we can get!

AVIATION

(18Z TAFS) Issued at 130 PM CDT Fri Sep 4 2026

VFR will prevail through the forecast period at all TAF sites. Expect southeasterly winds around 10 knots with occasional higher gusts through late this evening before falling to around 5-10 knots tonight. Winds should increase once again tomorrow by mid to late morning.

MARINE

Issued at 130 PM CDT Fri Sep 4 2026

Generally favorable marine conditions will continue through the forecast period with low seas and light to moderate southeasterly winds. Brief Small Craft Exercise Caution conditions cannot be ruled out each afternoon along the Laguna Madre and nearshore Gulf waters. Rain chances increase late this weekend and into next week over the Gulf waters and Laguna Madre, with near daily chances ranging from around 20-40%. Locally enhanced winds and seas are likely within and near any showers or thunderstorms.

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 81 99 81 98 / 0 10 10 40 HARLINGEN 77 102 77 101 / 0 20 0 40 MCALLEN 82 104 81 103 / 0 20 10 20 RIO GRANDE CITY 80 104 80 103 / 0 10 20 10 SOUTH PADRE ISLAND 82 90 82 90 / 0 10 10 20 BAYVIEW/PORT ISABEL 79 96 79 96 / 0 10 10 30

BRO WATCHES/WARNINGS/ADVISORIES

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