textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 612 AM CDT Fri Aug 28 2026

- Very hot, record to near record-breaking temperatures and rain- free conditions are expected to persist over the next week.

- Widespread Major (Level 3 of 4) with areas of Extreme (Level 4 of 4) Heat Risk is expected through mid next week.

- Worsening drought conditions are expected to continue due to the combination of very hot temperatures, antecedent dry conditions, and very high evaporation rates.

- The combination of dry fuels, lowering relative humidity values, and hot temperatures could lead to elevated fire danger risks through next week.

- There remains low (30% or less) chances for sea breeze showers/thunderstorms Friday through Sunday, particularly along and east of IH-69C/US-281.

DISCUSSION

Issued at 1001 PM CDT Thu Aug 27 2026

A broad and strong 591-594 dam sub-tropical heat dome will continue to yield hotter than normal temperatures through the middle parts of next week or into early September across Deep South Texas and the Rio Grande Valley. Record to near record-breaking temperatures are possible on Friday (see CLIMATE SECTION).

This heat dome will weaken some and begin shifting eastward from the 4-Corners Region to the southern Plains and Mid-South this weekend into next week. Given the situation, widespread triple digit heating including over Harlingen and Brownsville will still be possible through at least parts of the forecast period. Given the fact that climatologically we are in the hottest part of the year (i.e. average high temperature for McAllen is 100F degrees) and yet forecasted temperatures are projected to be 3-6F degrees hotter than the climatological peak temperatures will continue to result in dangerously hot conditions even for the RGV's standards in the days ahead. That said, widespread Major (Level 3 of 4) with areas of Extreme (Level 4 of 4) Heat Risk is expected to prevail through mid next week.

The combination of very hot temperatures and dry conditions will continue to result in very strong evaporation rates. This will lead to a continuation of worsening or expanding drought conditions across Deep South Texas and Rio Grande Valley during this stretch. A couple of models continue to hint at the potential for showers and thunderstorms along the sea breeze Friday through Sunday. Chances continue to remain low ranging between 20-30% with the best chances being along and east of IH-69C/US-281.

AVIATION

(12Z TAFS) Issued at 612 AM CDT Fri Aug 28 2026

Favorable flying conditions are anticipated at the aerodromes through the next 24 hours, with VFR prevailing.

MARINE

Issued at 1001 PM CDT Thu Aug 27 2026

Favorable marine conditions are expected to continue through mid next week with low to moderate seas (1 to 3 foot wave heights) and light to moderate southeasterly winds.

CLIMATE

Issued at 1001 PM CDT Thu Aug 27 2026

A massive and strong 591-594 dam heat dome situated over the Southwest U.S. and the Southern Plains will continue to result in record to near record-breaking temperatures through Friday. Daytime high temperature anomalies are expected to run 4-8F degrees above normal levels during this timeframe.

Below is a list of record highs for August 28:

Friday August 28th, 2026

Brownsville: 106F in 2023 Harlingen: 106F in 2011 McAllen: 107F in 2023

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 98 80 97 80 / 10 0 20 0 HARLINGEN 101 75 100 75 / 10 0 20 0 MCALLEN 104 80 103 80 / 10 10 10 0 RIO GRANDE CITY 104 78 103 78 / 0 10 0 0 SOUTH PADRE ISLAND 89 81 89 81 / 0 10 10 0 BAYVIEW/PORT ISABEL 96 78 95 78 / 0 0 10 0

BRO WATCHES/WARNINGS/ADVISORIES

None.