textproduct: Austin/San Antonio

KEY MESSAGES

Updated at 1200 AM 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

(Today through Friday) Issued at 1200 AM CDT Thu Aug 20 2026

A TUTT low feature will move west from South TX into Coahuila, Mexico by 00Z Friday. This shift will enable the large subtropical ridge center to shift east into NM from AZ, giving TX a larger share of the thermal ridge gradient beneath the east portion of the upper ridge. The eastern periphery of the TUTT low will be funneling low to mid level moisture inland. The shift of the upper ridge, daytime winds trending lower, and possibly some slightly higher afternoon dew points will probably combine to bring a mix of ambient temperatures and heat indices reaching Heat Advisory criteria, at least for the eastern counties today. No changes in the upper pattern is expected for Friday into the weekend, so it was decided in a prior shift to go with a multi-day NPW for the eastern half.

LONG TERM

(Friday night through Wednesday) Issued at 1200 AM CDT Thu Aug 20 2026

A weak backdoor front and pooling of mid level moisture is expected to approach the area from the NE Friday evening, then dissipating at the doorstep of Central TX. There could be one or two stray showers or storms to pop up in our far NE CWA, but we'll side with the drier solution given the strength of the ridge. A few cells are seen in the global runs for the following evening, so the pooled moisture and efficient heating will be something to monitor. The ridge should show it's peak dominance over TX by Sunday, continuing through next Wednesday as the 700 to 300 mb center axis becomes aligned over North TX. It's likely that additional heat headlines could be added for next week. The hottest air of the 2026 summer season is likely upon us, and there could be a high temperature record or two in jeopardy over the next week.

AVIATION

(06Z TAFS) Issued at 1200 AM CDT Thu Aug 20 2026

VFR conditions are expected through the period. There remains a low chance for brief 1.5 kft SCT to BKN ceilings near sunrise at I-35 terminals, but have only kept SCT coverage in the forecast at this time. Otherwise, any breezy wind will decrease in the next hour or so with light wind overnight. South to southeast wind reestablishes by the afternoon remaining mainly under 12 knots.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 103 78 104 79 / 0 0 0 0 Austin Bergstrom Intl Airport 103 78 103 79 / 0 0 0 0 New Braunfels Muni Airport 102 76 102 77 / 0 0 0 0 Burnet Muni Airport 101 76 101 77 / 0 0 0 0 Del Rio Intl Airport 102 79 102 78 / 0 0 0 0 Georgetown Muni Airport 102 79 103 79 / 0 0 0 0 Hondo Muni Airport 100 76 100 76 / 0 0 0 0 San Marcos Muni Airport 102 77 103 77 / 0 0 0 0 La Grange - Fayette Regional 103 77 104 78 / 0 0 0 0 San Antonio Intl Airport 102 79 102 79 / 0 0 0 0 Stinson Muni Airport 103 78 103 78 / 0 0 0 0

EWX WATCHES/WARNINGS/ADVISORIES

Heat Advisory from 2 PM this afternoon to 7 PM CDT Sunday for TXZ171>173-191>194-205>209-220>225.