Area Forecast Discussion
Issued by NWS Austin/San Antonio, TX
Issued by NWS Austin/San Antonio, TX
207 FXUS64 KEWX 291124 AFDEWX Area Forecast Discussion National Weather Service Austin/San Antonio TX 624 AM CDT Fri Aug 29 2025 .KEY MESSAGES... - Above average heat and humid today and Saturday, then near to below average temperatures Sunday into next week. - Rain chances northern Hill Country and Austin area today spreading south to include the San Antonio area on Saturday, then all areas Sunday into Monday. - Locally heavy rains possible today through Monday. The main threat is urban and small stream flooding with a marginal risk of flash flooding. && .SHORT TERM (THROUGH SATURDAY NIGHT)... A cold front lingers just to our north today through Saturday due to a weak northerly flow aloft providing little or no support for a farther south movement. Moisture convergence along the frontal zone will increase PWs to 150 percent of late August averages. Heating will generate showers and thunderstorms each afternoon into evening. The northerly flow aloft is just strong enough to bring this activity into the northern Hill Country to along the I-35 corridor as far south as the Austin area today, then the Edwards Plateau, Hill Country to along and east of the I-35 corridor as far south as the San Antonio area on Saturday. The fairly efficient rainfall processes along with rather slow storm motions will bring locally heavy rains and a threat of flooding to those areas mentioned above. Spotty rainfall amounts up to 3 inches are possible. WPC has a marginal risk (level 1 of 4) for excessive rains leading to flash flooding for those areas. However, the main threat is urban and small stream type flooding. Due to moist and unstable airmass, wind gusts to 50 mph are possible with the strongest storms. The hot, above late August temperatures seen on Thursday will continue today and Saturday most areas as the front stays to our north and the showers and thunderstorms holding off until peak heating. With increasing PWs, dewpoints will not mix as efficiently as the last few days keeping afternoon heat indices a little more elevated possibly briefly reaching heat advisory levels of 108 or so. && .LONG TERM (SUNDAY THROUGH THURSDAY)... A stronger northerly flow aloft develops Sunday and Monday allowing the front to move across our area. Forcing by the front and heating will generate showers and thunderstorms over most areas. Moisture levels increase further to near 200 percent of late August/early September averages. Thus, spots of heavy rain are more likely with rainfall amounts up to 5 inches possible due to efficient rainfall processes and slow or repeat storm motions. Should these rains fall over areas with earlier heavy rains, then the threat for flash flooding will increase. However, the main threat remains urban and small stream type flooding. WPC has a marginal risk (level 1 of 4) for excessive rains leading to flash flooding for all of our area. Due to the moist and unstable airmass, wind gusts to 40 mph are possible. With the clouds and rain areas, as well as weak cold advection, temperatures will fall to slightly below late August into early September averages. With a stronger northerly flow aloft, the models are trending drier for middle to late next week. However, will maintain low to slight chances of rain for the possibility of impulses in the flow aloft and another cold frontal passage. Though those features are highly uncertain, at this time. Temperatures warm to early September average. && .AVIATION (12Z FRIDAY THROUGH SATURDAY)... VFR conditions are forecast for the local terminals for the most part. Some low clouds are forecast to develop near KAUS by daybreak. Confidence is low for MVFR cigs, but can`t be ruled out for an hour or two between 12Z and 15Z. A cold front is forecast to stay to our north this afternoon and evening, however, isolated to scattered showers and storms are forecast to develop ahead of it and push to the south into the Austin metro area. With the loss of daytime heating, most of the activity comes to an end in the evening. For the San Antonio and Del Rio airports, VFR conditions persist through the period. A southeast to south wind flow of 3 to 12 knots with gusts up to 20 knots is forecast through this aviation cycle. && .PRELIMINARY POINT TEMPS/POPS... Austin Camp Mabry 76 96 75 90 / 20 40 40 70 Austin Bergstrom Intl Airport 76 97 75 90 / 10 40 40 70 New Braunfels Muni Airport 75 99 74 94 / 10 30 30 60 Burnet Muni Airport 74 93 73 85 / 20 60 50 80 Del Rio Intl Airport 79 102 79 99 / 0 0 10 30 Georgetown Muni Airport 75 92 73 86 / 20 60 50 70 Hondo Muni Airport 75 100 74 97 / 0 10 20 50 San Marcos Muni Airport 75 99 74 94 / 10 30 30 60 La Grange - Fayette Regional 76 95 75 90 / 10 40 40 70 San Antonio Intl Airport 77 100 77 96 / 10 20 30 50 Stinson Muni Airport 78 101 78 98 / 10 10 20 50 && .EWX WATCHES/WARNINGS/ADVISORIES... None. && $$ Short-Term...04 Long-Term...04 Aviation...17