textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 933 PM CDT Mon Aug 24 2026

- Very hot, record to near record-breaking temperatures and rain- free conditions are expected to persist through this week.

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

- Low (20% or less) chances for sea breeze showers/thunderstorms Friday through next weekend, particularly along and east of IH-69C/US-281; something worth monitoring in the days ahead.

DISCUSSION

Issued at 933 PM CDT Mon Aug 24 2026

A massive and anomalously strong 594-598 dam heat dome, that's resulting in a dangerous heat wave across the Southwest U.S. and Southern Plains, will continue to yield hotter than normal, record to near record-breaking temperatures over Deep South Texas and the Rio Grande Valley through next weekend and for that matter through the month of August (see CLIMATE SECTION).

Widespread triple digit heating including over Harlingen and Brownsville will continue through the forecast period as the aforementioned heat dome remains parked over the 4-Corners Region. 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 4-8F degrees hotter than the climatological peak temperatures will result in dangerously hot conditions even for the RGV's standards in the days ahead. That said, widespread Major (Level 3 of 4) with increasing areas of Extreme (Level 4 of 4) Heat Risk is expected through next weekend.

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 have been hinting at the potential for showers and thunderstorms along the sea breeze Friday through next weekend. Right now, the chances are too low, nonetheless, this will be something that needs monitoring in the coming days.

AVIATION

(00Z TAFS) Issued at 520 PM CDT Mon Aug 24 2026

Through 00z Wednesday...VFR conditions will prevail through the 00z TAF cycle.

Winds will continue out of the south-southeast 5-15 kts through the forecast period. Winds could gusts to between 20-25 kts during the afternoon/evening hours.

MARINE

Issued at 933 PM CDT Mon Aug 24 2026

Favorable marine conditions are expected to continue through next weekend with low seas (1 to 2 foot wave heights) and light to moderate southeasterly winds.

CLIMATE

Issued at 933 PM CDT Mon Aug 24 2026

A massive and strong 594-598 dam heat dome situated over the Southwest U.S. and the Southern Plains will result in record to near record-breaking temperatures during the workweek. Daytime high temperature anomalies are expected to run 4-8F degrees above normal levels during this timeframe.

Below is a list of record highs from August 25-28:

Tuesday August 25th, 2026

Brownsville: 100F in 2019 Harlingen: 103F in 1924 McAllen: 105F in 2019

Wednesday August 26th, 2026

Brownsville: 101F in 2019 Harlingen: 103F in 1924 and 1948 McAllen: 104F in 2019 and 2018

Thursday August 27th, 2026

Brownsville: 102F in 2023 Harlingen: 104F in 1948 McAllen: 105F in 2018

Friday August 28th, 2026

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

PRELIMINARY POINT TEMPS/POPS

BROWNSVILLE 80 99 81 99 / 0 0 0 0 HARLINGEN 76 103 77 102 / 0 10 0 0 MCALLEN 79 104 80 104 / 0 0 0 0 RIO GRANDE CITY 78 105 78 105 / 0 0 0 0 SOUTH PADRE ISLAND 81 90 81 90 / 0 0 0 0 BAYVIEW/PORT ISABEL 78 97 79 97 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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