textproduct: Austin/San Antonio

KEY MESSAGES

Updated at 241 PM CDT Thu Aug 20 2026

- Heat Advisory in effect form the northern Hill Country, I-35 Corridor, and Coastal Plains Thursday-Sunday.

- August heat wave continues with no rain or heat relief in sight.

SHORT TERM

(Tonight through Friday night) Issued at 241 PM CDT Thu Aug 20 2026

Surface high pressure over the Four Corners is stretching over Texas today. A tropical upper tropospheric trough (TUTT) was to the south over Mexico will linger and weaken to close out the week and start the weekend. A larger scale mid to upper level trough will amplify over the eastern United States, pushing a weak back door front into North Texas. The ridge will build back in over Texas fairly quickly on Saturday in the wake of this.

Additional surface moisture advecting north ahead of the backdoor front could help drive higher heat index readings. Maximum temperatures will continue to range from the upper 90s in the Edwards Plateau and Texas Hill County to the lower to mid 100s along and east of the I-35 corridor. For overnight lows, 70s will be the main story though preferred a solution closer to the NBM 25th percentile which was closer to recent observed trends and bias- adjusted model guidance. Similar was the story for hourly dewpoints in the short term portion of the forecast.

LONG TERM

(Saturday through next Thursday) Issued at 241 PM CDT Thu Aug 20 2026

The ridge of high pressure will hold over the region over the rest of the weekend and continue building as the work week kicks off. By mid-week, the center will slide between New Mexico and Texas keeping a warm, sunny pattern on tap for the region. The scale of the heat will need to be monitored in upcoming forecast cycles in case the heat wave threatens some daily maximum temperature records.

AVIATION

(18Z TAFS) Issued at 119 PM CDT Thu Aug 20 2026

Generally VFR with a southerly wind flow that could become gusty at times through the evening. Lighter wind later tonight with some directional variability possible before the wind flow picks up again.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 78 105 79 106 / 0 0 0 0 Austin Bergstrom Intl Airport 78 104 78 105 / 0 0 0 0 New Braunfels Muni Airport 76 103 76 104 / 0 0 0 0 Burnet Muni Airport 76 102 76 103 / 0 10 10 0 Del Rio Intl Airport 78 103 77 104 / 0 0 0 0 Georgetown Muni Airport 78 104 79 104 / 0 0 0 0 Hondo Muni Airport 76 101 75 102 / 0 0 0 0 San Marcos Muni Airport 76 103 76 104 / 0 0 0 0 La Grange - Fayette Regional 77 104 77 104 / 0 0 0 0 San Antonio Intl Airport 78 102 78 103 / 0 0 0 0 Stinson Muni Airport 77 104 77 104 / 0 0 0 0

EWX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 7 PM CDT Sunday for TXZ171>173-191>194- 205>209-220>225.