Area Forecast Discussion

KEY MESSAGES

Updated at 602 PM CDT Tue Jul 21 2026

- Major to Moderate flooding on the Nueces and Frio River basins to continue. Elevated flows on area rivers continue to ease.

- Heat Advisory is in effect Wednesday for areas generally along and east of the Interstate 35 corridor.

- Tropical Storm Bertha over the northeast Gulf will continue to be monitored for for possible forecast impacts on south central Texas.

SHORT TERM

(Tonight through Wednesday night) Issued at 131 PM CDT Tue Jul 21 2026

Dry weather along with a warming trend will continue across south central Texas today and Wednesday. Highs today are still on track to peak in the lower 90s to near 100 degrees. While a few spots in the coastal plains may see peak heat index values near 106 degrees, we should remain below Heat Advisory levels today.

On Wednesday, a slight strengthening of the low-level thermal ridge will occur along with a bump in low-level moisture. In addition, we expect to see a decrease in afternoon wind speeds and this will serve to reduce afternoon mixing of dew points. With warmer temperatures and moisture levels remaining higher, a Heat Advisory has been issued for areas generally along and east of Interstate 35 for Wednesday afternoon. For ares within the Heat Advisory, look for high temperatures of 100 to 104 along with heat index values up to 112 degrees. Elsewhere, it will remain hot as well with highs in the mid 90s to near 105 along the Rio Grande south of Eagle Pass.

LONG TERM

(Thursday through next Tuesday) Issued at 131 PM CDT Tue Jul 21 2026

On Thursday, we expect to see a fairly deep east to northeast flow through most of the atmosphere. While the low-level thermal ridge axis should be nudged westward slightly, still suspect a good portion of locations along and east of Interstate 35 will likely be at or just above the heat index threshold of 108 degrees. If this pans out, we would need another Heat Advisory for the above mentioned areas on Thursday. While most of the region will remain dry, we do have a very low chance for afternoon convection near the coastal plains.

The forecast for the remainder of the week will likely depend on the eventual track of current Tropical Storm Bertha in the northeast Gulf. The medium range models continue to be reluctant to show much in the way of precipitation chances across our region. For the remainder of the forecast, we will continue the current trend of near to slightly above normal temperatures along with dry weather.

AVIATION

(00Z TAFS) Issued at 602 PM CDT Tue Jul 21 2026

VFR conditions prevail through this TAF window. Winds will be light and variable tonight, increasing to around 8-10 knots Wednesday afternoon. Chances for MVFR vis/cigs are low Wednesday morning, generally less than 20%. However, some patchy fog can't be ruled out.

PRELIMINARY POINT TEMPS/POPS

EWX WATCHES / WARNINGS / ADVISORIES

Heat Advisory from noon to 8 PM CDT Wednesday for TXZ171>173- 191>194-204>209-219>225.