textproduct: Austin/San Antonio

KEY MESSAGES

Updated at 641 PM CDT Tue Sep 29 2026

- A Flood Watch is in effect from Wednesday evening through Friday evening for much of South Central Texas. Heavy rainfall may lead to life-threatening flash flooding somewhere in the Watch area.

- Some storms Wednesday night through Friday morning may become strong to severe with strong wind and hail the main hazards. Flooding continues to be the main concern.

- Low to medium rain changes linger through the weekend then decrease heading into next week.

SHORT TERM

(Tonight through Wednesday night) Issued at 148 PM CDT Tue Sep 29 2026

A closed upper low is currently located over the AZ/CA boarder with a weakening Hurricane Polo's low level circulation moving towards far West Texas late today then generally tracking to the north. Eventually a more classic surface low develops on the lee side of the Rockies with a Pacific cold front extending into Texas which will be the predominant feature bringing our widespread rain chances mid to late week.

For today, low level moisture increases as moderate onshore flow builds over the area. An increase in clouds and hot and humid conditions continue this afternoon with widespread highs in the 90s to around 100 degrees and heat index values generally up to 105-107 degrees. Scattered showers and thunderstorms are favored over the coastal plains and possibly into the I-35 corridor this afternoon and evening before dissipating. Later this evening, a weakening line of showers and thunderstorms may push into the southern Edwards Plateau which could continue into the early morning hours associated with a disturbance rounding the base of the upper low. Cannot rule out a quick inch or two tonight over this area if storms remain organized.

Conditions remain breezy overnight into Wednesday with continued moisture pooling over the area evident by PWATS at or exceeding 2 inches in the western half of the area by Wednesday morning. Hot and humid conditions will continue this day as our Pacific front remains west of the area during the day. A few showers and thunderstorms will be possible during the day but should be relatively isolated in nature.

Attention then turns to Wednesday night as a line of showers and thunderstorms builds into the southern Edwards Plateau and slowly shifts east across the area into Thursday morning. There is some uncertainty if it completely builds over the Rio Grande Plains or a more broken line evolves. Either way, high moisture will lead to thunderstorms capable of producing heavy rain which can lead to flash flooding. WPC continues a level 3 of 4 risk for flooding overnight through Thursday morning over southern Edwards Plateau and western Hill Country. Additionally, there is a level 1 of 5 risk for severe weather with this line of storms with strong wind the main concerns.

A Flood Watch has been issued beginning Wednesday night and continuing into Friday evening. More on potential flooding in the extended.

LONG TERM

(Thursday through next Tuesday) Issued at 148 PM CDT Tue Sep 29 2026

Rain chances peak Thursday into Friday as the slow moving front remains over South Central Texas. There remains some uncertainty if this front continues to propagate east or gets hung up somewhere over the area. The latter of those two scenarios would be worse for flooding impacts as stalled storms could linger over areas for multiple hours. Another consideration is we may see storm activity weaken during the morning hours, but the lingering boundary and peak heating will regenerate any shower and thunderstorm activity by the afternoon which will likely continue into Friday morning. The level 3 of 4 risk continues over a large portion of the area on Thursday and Thursday night including the Hill Country and I-35 corridor where average rainfall totals of 2-4 inches with isolated amounts up to 8 inches remain possible.

Exactly how things evolve Friday is still a bit blurred but overall the surface front will remain near South Central Texas and a moisture rich environment and upper low to the west will keep medium chances for rain in the forecast. If the front progresses east this rain will focus more over the coastal plains Friday but some guidance continues to show redevelopment of storms further west which could exacerbate any previous flooding.

For the upcoming weekend, some remnant upper level energy may hang back to our west as 'Rachel' continues in the eastern Pacific. While our western areas may see slightly lower moisture levels, we will still have plenty of moisture to work with farther east into the I- 35 corridor and coastal plains. Rain chances will remain in the forecast for the weekend into Monday. With good precipitation chances, northerly winds in the lower levels and cloud cover, highs will generally range from the mid 70s to the lower 80s along with overnight lows in the 60s.

AVIATION

(00Z TAFS) Issued at 641 PM CDT Tue Sep 29 2026

VFR Cigs are expected for the rest of this evening at all I-35 TAF sites. Breezy S/SE winds of 10-15 knots with gusts as high as 26 knots can be expected. Winds should settle down by the beginning overnight hours along with MVFR CIGs developing due to the influx of moisture being pumped up from the Gulf. This low cloud deck should eventually erode by the early afternoon hours tomorrow with VFR CIGs returning. Winds really increase by the late afternoon hours with breezy S/SE winds of 10-15 knots and gusts up to 27 knots. Lastly, as the front progresses eastward we could see convection begin to form right towards the end of this forecast period for KAUS and KSAT. Have kept PROB30s out of this package for now but they will likely be needed in the next TAF package. For KDRT similar conditions with breezy S/SE winds can be expected before MVFR CIGs commence overnight and winds calm down. Could also see some showers form near the terminal for a few hours so have kept mention of VCSH. Otherwise expect VFR CIGs to return by late morning tomorrow.

PRELIMINARY POINT TEMPS/POPS

Austin Camp Mabry 76 95 76 91 / 10 20 40 100 Austin Bergstrom Intl Airport 75 95 75 91 / 10 20 40 90 New Braunfels Muni Airport 74 96 75 91 / 10 20 40 90 Burnet Muni Airport 73 92 74 85 / 10 20 60 100 Del Rio Intl Airport 77 96 74 90 / 40 20 80 80 Georgetown Muni Airport 75 94 75 89 / 10 30 50 100 Hondo Muni Airport 75 96 74 87 / 10 20 70 100 San Marcos Muni Airport 74 95 75 91 / 10 20 40 90 La Grange - Fayette Regional 75 96 76 94 / 10 20 40 90 San Antonio Intl Airport 77 95 77 88 / 10 20 50 100 Stinson Muni Airport 77 97 77 90 / 10 20 40 90

EWX WATCHES/WARNINGS/ADVISORIES

Flood Watch from Wednesday evening through Friday evening for TXZ171>173-183>193-202>208-217>221-223-228.