textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 617 PM CDT Thu Sep 3 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 relative humidity, dry grasses, and hot temperatures may raise concerns for favorable fire weather through Friday.

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

DISCUSSION

Issued at 115 PM CDT Thu Sep 3 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 this weekend and continue into next week. A Heat Advisory remains in effect through 6 PM this evening due to the combination of hot temperatures and elevated humidity, resulting in heat index values up to 114 degrees. Additional heat headlines may be needed through Saturday as the region remains under the influence of mid/upper level ridging aloft. Temperatures are expected to run around 5-7 degrees above normal for early September, although historical data from Labor Day indicate 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, the combination of above normal temperatures and elevated humidity will continue to yield heat index values ranging from 106-113 degrees each afternoon through at least 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 and Wednesday. Well take what we can get!

AVIATION

(00Z TAFS) Issued at 617 PM CDT Thu Sep 3 2026

VFR conditions will prevail through the TAF period. Expect southeasterly winds to decease overnight.

MARINE

Issued at 115 PM CDT Thu Sep 3 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 early 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.

CLIMATE

Issued at 115 PM CDT Thu Sep 3 2026

Near record to record breaking temperatures are expected through at least early September. Here are the daily records for Brownsville, Harlingen, and McAllen through this Friday.

Thursday, September 3

Brownsville: 102F (2011) Harlingen: 106F (2011) McAllen: 106F (2011)

Friday, September 4

Brownsville: 103F (2011, 2000) Harlingen: 107F (2011) McAllen: 108F (2011)

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 82 98 81 98 / 0 0 10 10 HARLINGEN 78 102 78 101 / 0 0 0 20 MCALLEN 82 104 82 103 / 0 0 0 20 RIO GRANDE CITY 80 105 80 103 / 0 0 0 10 SOUTH PADRE ISLAND 82 90 82 90 / 0 0 10 10 BAYVIEW/PORT ISABEL 79 96 79 96 / 0 0 10 10

BRO WATCHES/WARNINGS/ADVISORIES

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