textproduct: Brownsville/Rio Grande Valley

KEY MESSAGES

Updated at 1221 AM CDT Thu Aug 27 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 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 this week.

- 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 947 PM CDT Wed Aug 26 2026

A broad and anomalously strong 594-598 dam sub-tropical 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 mid next week into early September (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 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 have increased over the past 24 hours, but still remain low ranging between 20-30% with the best chances being along and east of IH- 69C/US-281. This certainly is something that needs monitoring in the coming days as we can certainly use the rain.

AVIATION

(06Z TAFS) Issued at 1221 AM CDT Thu Aug 27 2026

Favorable flying conditions are expected for the TAF period, with limited cloud cover and light to moderate winds with breezy daytime gusts.

MARINE

Issued at 947 PM CDT Wed Aug 26 2026

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

CLIMATE

Issued at 947 PM CDT Wed Aug 26 2026

A massive and strong 594-598 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 from August 27-28:

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 99 80 98 80 / 0 0 10 0 HARLINGEN 102 76 101 76 / 0 0 10 0 MCALLEN 104 80 104 80 / 0 0 10 0 RIO GRANDE CITY 104 78 104 78 / 0 0 0 0 SOUTH PADRE ISLAND 89 81 89 81 / 0 0 0 0 BAYVIEW/PORT ISABEL 96 78 96 78 / 0 0 0 0

BRO WATCHES/WARNINGS/ADVISORIES

None.