textproduct: Austin/San Antonio

KEY MESSAGES

- Hazardous heat expected Thursday across South-Central Texas.

- Hot and humid weather continues into next week.

- Isolated rain chances Thursday night with broader chances Friday night into Saturday.

SHORT TERM

(Today through Friday) Issued at 116 AM CDT Thu Jun 18 2026

Post-tropical storm Arthur has brought an upper level trough over TX. The low level flow is from the southeast keeping a warm, moist airmass over South-Central Texas. Temperatures are 1-5 degrees warmer and dewpoints are about the same as 24 hours ago. As what is left of Arthur moves away to the northeast, the subtropical ridge will build back in behind it. The big concern for our CWA today will be rising heat and humidity. The combination of hot temperatures and high humidity will result in heat indices above 110 degrees for most of the area. An Excessive Heat Warning remains in effect for the I- 35 Corridor, Coastal Plains, and southern Rio Grande Plains with a Heat Advisory everywhere else. A weak cold front will move into Central Texas and lift from this boundary could produce some showers or thunderstorms tonight over the Hill Country and Southern Edwards Plateau. Friday winds will shift to a little more easterly direction and temperatures and dewpoints will be a little lower. The resulting heat indices will also be lower. A Heat Advisory may be needed for the I-35 Corridor, the Coastal Plains, and the southern Rio Grande Plains, but the rest of the CWA should be below criteria.

LONG TERM

(Friday night through Wednesday) Issued at 116 AM CDT Thu Jun 18 2026

The weak frontal boundary will move back northward as a warm front. At the same time deeper layer moist air will surge from the Gulf over our CWA. This combination will result in an increased chance for showers and thunderstorms Friday night and Saturday. PW will be high enough that locally heavy rain will be possible. The subtropical ridge will build back over TX Sunday into Monday bringing back dry weather. Temperatures will warm to near normal for the last few days of this forecast. With humidity added in the heat indices will be 100-105 for the area along and south of I-35/Hwy 90. We should stay below heat advisory criteria.

AVIATION

(12Z TAFS) Issued at 532 AM CDT Thu Jun 18 2026

Little change to the going forecast as it remains on track. IFR ceilings have developed at SAT and SSF and MVFR remains at AUS through late morning before VFR returns at all three sites. A brief period of IFR stratus is possible at AUS, so a TEMPO group has been utilized. Winds will increase to 10-12 kts along with occasional gusts this afternoon. MVFR ceilings return once again around midnight tonight.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 98 80 94 78 / 0 10 20 50 Austin Bergstrom Intl Airport 98 80 94 78 / 0 10 20 40 New Braunfels Muni Airport 98 79 94 77 / 0 10 20 40 Burnet Muni Airport 97 78 92 75 / 0 30 20 60 Del Rio Intl Airport 105 81 98 77 / 0 30 40 40 Georgetown Muni Airport 97 79 93 77 / 0 20 20 50 Hondo Muni Airport 99 79 93 76 / 0 10 20 50 San Marcos Muni Airport 97 79 94 77 / 0 10 20 40 La Grange - Fayette Regional 97 80 93 79 / 0 10 20 40 San Antonio Intl Airport 98 80 94 78 / 0 10 20 40 Stinson Muni Airport 98 79 94 78 / 0 10 30 40

EWX WATCHES/WARNINGS/ADVISORIES

Heat Advisory from noon today to 8 PM CDT this evening for TXZ171-172-183>190-202.

Extreme Heat Warning from noon today to 8 PM CDT this evening for TXZ173-191>194-203>209-217>225-228.