textproduct: Brownsville/Rio Grande Valley

DISCUSSION

Issued at 941 PM CDT Tue Sep 8 2026

Hot, mainly dry, and at times breezy conditions will continue to be the main weather storyline through early next week as an anomalously strong and elongated 591-594 dam heat ridge complex remains anchored over the southern U.S. This persistent and dominant feature in our pattern will continue to foster record to near record-breaking heat over the next several days (see CLIMATE SECTION for more details). High temperatures are progged to continue to climb into the upper 90s to mid 100s through the forecast period with overnight lows in the 70s to lower 80s. Peak heat indices ranging between 105-115F degrees will continue to warrant day-to-day or near daily Special Weather Statements (SPSs) and/or Heat Advisories through this week. The combination of very hot temperatures during the day and very warm temperatures at night providing little relief, widespread Major (Level 3 of 4) Heat Risk to increasing areas of Extreme (Level 4 of 4) Heat Risk will be the case through this week (at least).

Aided by persistent southeasterly winds, low-medium (20-40%) chances for showers and thunderstorms along the sea breeze is possible through Thursday as Deep South Texas sits on the on the southern periphery of the aforementioned heat ridge. The best chances for any showers and storms will be along and east of IH- 69C/US-281.

AVIATION

(00Z TAFS) Issued at 613 PM CDT Tue Sep 8 2026

Through 00z Thursday....By and large, VFR conditions are expected to prevail through the 00z TAF cycle. Scattered showers and thunderstorms along the sea breeze are expected to develop during the afternoon hours, coinciding with peak daytime heating. Have introduced Prob30 groups to account for the potential for sea breeze showers and thunderstorms on Wednesday. Any showers or thunderstorms that move over a TAF site will have the capabilities of briefly reducing cigs/visibilities down to MVFR/IFR range. Otherwise, expect for VFR conditions to persist with a SCT cumulus field overhead.

Southeast winds 10-20 kts with gusts as high as 25 kts this evening will diminish as the evening wears on. Tonight, winds will be light and variable to calm. On Wednesday, winds will pick up out of the southeast once again with speeds between 10-20 kts and gusts as high as 25 kts or so (particularly during the afternoon/evening hours).

MARINE

Issued at 941 PM CDT Tue Sep 8 2026

Outside of any showers or thunderstorms, marine conditions will remain favorable through this week with low to moderate winds and low seas (i.e. wave heights between 1-3 feet). Moderate seas are possible over the weekend into early next week.

CLIMATE

Issued at 941 PM CDT Tue Sep 8 2026

Record to near record-breaking temperatures are possible through Saturday, courtesy of a persistent and strong 591-594 dam heat ridge complex established over the southern U.S. Below is a list of the record highs from Wednesday September 9th to Saturday September 12th.

Wednesday September 9, 2026:

Brownsville: 102F in 1893 Harlingen: 102F in 2023 McAllen: 103F in 2023 & 2016

Thursday September 10, 2026:

Brownsville: 102F in 2023 Harlingen: 102F in 2023 McAllen: 105F in 2023

Friday September 11, 2026:

Brownsville: 100F in 1900 & 1893 Harlingen: 103F in 1937 McAllen: 103F in 2023

Saturday September 12, 2026:

Brownsville: 100F in 1919 Harlingen: 101F in 2011 & 1930 McAllen: 103F in 1987

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 81 97 80 98 / 10 30 0 30 HARLINGEN 77 100 76 102 / 0 30 0 20 MCALLEN 81 103 80 104 / 0 30 10 10 RIO GRANDE CITY 79 104 78 104 / 10 10 10 10 SOUTH PADRE ISLAND 82 89 81 90 / 10 10 0 20 BAYVIEW/PORT ISABEL 79 95 78 96 / 0 20 0 20

BRO WATCHES/WARNINGS/ADVISORIES

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