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

(18Z TAFS) Issued at 1226 PM CDT Thu Jun 18 2026

VFR flight conditions are to persist from this afternoon through this evening with few to sct mid-level clouds and increasing high level clouds. There is the potential but of low confidence for isolated to scattered convection with a complex or two approaching the region late this evening out west, towards KDRT, and tomorrow morning into the afternoon from the Hill Country into the I-35 corridor. For this potential, added in a PROB30 group with -TSRA for 00Z to 04Z at KDRT, and 18Z to 00Z tomorrow at the 30 hour TAF sites at KSAT and KAUS. Otherwise, MVFR to IFR ceilings are to be expected to develop and expand across the region from the latter half of the overnight through much of Friday morning. Friday afternoon should see conditions to return VFR levels. Winds remain light to moderate from the east to southeast but could become temporarily higher within or near any convective activity.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 79 94 78 92 / 20 30 40 50 Austin Bergstrom Intl Airport 80 93 78 92 / 10 30 40 50 New Braunfels Muni Airport 79 93 77 91 / 10 30 40 50 Burnet Muni Airport 78 91 75 91 / 30 40 40 40 Del Rio Intl Airport 82 97 77 95 / 20 40 40 10 Georgetown Muni Airport 79 92 77 91 / 20 40 40 50 Hondo Muni Airport 79 93 76 91 / 20 20 50 30 San Marcos Muni Airport 79 93 77 92 / 10 30 40 50 La Grange - Fayette Regional 80 93 79 91 / 0 30 40 50 San Antonio Intl Airport 80 93 78 91 / 10 20 40 50 Stinson Muni Airport 79 93 78 92 / 10 20 50 50

EWX WATCHES/WARNINGS/ADVISORIES

Heat Advisory until 8 PM CDT this evening for TXZ171-172-183>190- 202.

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