textproduct: Austin/San Antonio

KEY MESSAGES

- Concern for locally heavy rain with isolated instances of flash flooding during the overnight into this morning; greatest area of concern along and south of the I-10/US Highway 90 corridor.

- Lingering of low to medium (20-40%) rain and storm chances for this afternoon through Sunday morning before a drier pattern establishes.

- Summer heat featuring elevated heat indices through next week.

SHORT TERM

(Tonight through Sunday night) Issued at 1035 PM CDT Fri Jun 19 2026

A lull in activity occurred through the evening hours behind the outflow/frontal boundary that had advanced across the region earlier today. That boundary had sparked some isolated to scattered rain and storms but also some significant relief to the hazardous heat we had experienced recently. Several short term guidance members show an increase in rain and storm coverage into and through the overnight hours tonight, with the greatest concentration generally near and to the south of the I-10/US HWY 90 corridor. This could be associated with or at least an extension of a storm complex that has developed just to the west of the Rio Grande across Mexico down by Laredo. The activity may also connect with the nearby boundary, sparking additional activity. Rainfall rates with the overnight activity could become quite heavy with rates in excess of 2-3 inches per hour at times. Given this potential, isolated instances of flash flooding will remain possible. Activity could push south or southeastward into the CRP CWA near or not too long after sunrise. I'll continue to note that the confidence on the rain and storms remains low given the chaotic nature of the recent storm complexes within the weak steering flow aloft.

Later today remains dependent on how the atmosphere recovers from the possible overnight into early morning activity. Overall, heat indices should remain below heat advisory criteria but could reach in excess of 100 degrees for locations along the I-35 corridor, and within the Coastal and Rio Grande Plains. Enough instability could establish with daytime heating where isolated to scattered shower and storm activity will be possible from the afternoon into the night, mainly to the east of the Rio Grande. Activity may linger into Sunday morning.

Sunday afternoon then looks to start the drying trend regarding the area rain chances and this continues onward into the long term as the long term forecast discussion below highlights. Mid-level ridging remains in control to our west along the Arizona/New Mexico border and Northern Mexico. It expands a bit father east into West Texas Sunday and this would kick the broad troughiness that is over the region currently, to the east. Heat then returns to being the primary story with the afternoon highs in the mid to upper 90s and heat indices peaking between 100 to 110 degrees. We'll monitor area extent of the heat indices near or above 108 as we get closer in time to evaluate a possible issuance of a Heat Advisory.

LONG TERM

(Monday through next Saturday) Issued at 1035 PM CDT Fri Jun 19 2026

Mid-level ridging remains anchored through much of the long term period to our west across Northern Mexico to near or just south of the Arizona/New Mexico border. The eastern periphery of the ridge will continue to push into West Texas. For South-Central Texas, we'll remain under a northerly flow aloft. The forecast will remain mostly rain free but with the northerly flow, we'll have to keep a close eye on any convection to the north that would try to slide southward. For now, majority of the guidance favors keeping the activity across Oklahoma/Arkansas with some activity reaching southward into the northern half of Texas. Otherwise, a persistent south-southeasterly low-level flow will keep hot and humid weather in place with elevated heat indices. Afternoon highs generally remain in the mid 90s while the overnight lows fall into the mid to upper 70s.

AVIATION

(12Z TAFS) Issued at 552 AM CDT Sat Jun 20 2026

Convection has waned over the region with the few remaining active cells well away from the TAF locations. A few hours of recovery in VFR skies are allocated for, before returning low MVFR level CIGs to the area for a few hours. Convection in the afternoon is expected to be sparse enough to disregard, but some wind gust impacts may need consideration later today. Tonight's cloud forecast reverts to the typical diurnal trends assuming a fresh coat of rainfall for all.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 91 77 95 78 / 30 10 20 0 Austin Bergstrom Intl Airport 91 77 94 79 / 30 10 20 0 New Braunfels Muni Airport 91 77 94 77 / 30 20 20 0 Burnet Muni Airport 89 76 93 77 / 30 10 10 0 Del Rio Intl Airport 93 77 96 79 / 10 0 0 0 Georgetown Muni Airport 90 77 94 78 / 40 10 10 0 Hondo Muni Airport 91 76 94 77 / 30 20 20 0 San Marcos Muni Airport 90 77 94 77 / 30 20 20 0 La Grange - Fayette Regional 91 78 93 79 / 50 20 20 0 San Antonio Intl Airport 90 78 93 78 / 30 30 20 0 Stinson Muni Airport 91 78 93 78 / 30 30 20 0

EWX WATCHES/WARNINGS/ADVISORIES

None.