textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1233 AM 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.

DISCUSSION

Issued at 1017 PM CDT Sun Aug 23 2026

An anomalously strong, sprawling 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). To put into context how persistent the heat has been, Brownsville and Harlingen today recorded its 6th and 7th consecutive 100F degree day, respectively amid this strong and vast heat dome.

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. Furthermore, wildfire concerns will also remain on the table through next weekend as relative humidity (RH) levels drop during the afternoon hours to near Fire Danger Statement (RFD) criteria on already dry fuels. Winds and RH value trends will need to be closely monitored through next weekend for the potential issuance of a Fire Danger Statement.

AVIATION

(06Z TAFS) Issued at 1233 AM CDT Mon Aug 24 2026

VFR conditions are forecast to continue through the TAF period. Light and variable winds overnight are forecast to increase out of the southeast late Monday morning, with gusts increasing through the afternoon.

MARINE

Issued at 1017 PM CDT Sun Aug 23 2026

Favorable marine conditions are expected throughout the week with low seas (1 to 2 foot wave heights) and light to moderate southeasterly winds.

CLIMATE

Issued at 1017 PM CDT Sun Aug 23 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 24-28:

Monday August 24th, 2026

Brownsville: 100F in 1970 Harlingen: 102F in 2010, 1936, & 1952 McAllen: 105F in 2018

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 98 80 98 81 / 0 0 0 0 HARLINGEN 102 76 102 77 / 0 0 10 0 MCALLEN 104 80 104 80 / 0 0 0 0 RIO GRANDE CITY 104 78 105 78 / 0 0 0 0 SOUTH PADRE ISLAND 89 81 90 81 / 0 0 0 0 BAYVIEW/PORT ISABEL 97 78 97 79 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

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