High pressure system keeps South Central Texas in relentless heat wave

A minima chance of rain Thursday

Shelby Ebertowski, KSAT Weather Authority Meteorologist

Published: August 23, 2026 at 5:57 AMUpdated: August 23, 2026 at 6:07 AM

FORECAST HIGHLIGHTS

SUNDAY: Dangerous heat with highs in the 103°-107° range across many areas.
HEAT ALERT: Extreme Heat Warning and Heat Advisories continue for portions of the region.
WEEK AHEAD: Little change expected with 100°+ temperatures and limited rain chances through midweek.

FORECAST

After San Antonio reached 103 degrees Saturday, the hottest temperature of the summer so far, Sunday will bring more of the same.

MORE TRIPLE DIGIT HEAT TODAY

An Extreme Heat Warning is in effect until 7 p.m. Sunday for Caldwell, Fayette, Gonzales, and Lavaca counties, with highs up to 107° and heat indices reaching 110°. A Heat Advisory follows from 7 p.m. Sunday through 7 p.m. Wednesday including Bexar County, with temperatures up to 105°. Residents should take precautions to avoid heat-related illness.

San Antonio will hit triple digits again today. While lower humidity may keep heat index values near actual temperatures, the extreme heat remains dangerous for those outdoors.

THE HEAT ISN’T LEAVING ANYTIME SOON

High pressure will keep South Central Texas hot and dry through at least Wednesday. With temperatures remaining above 100 degrees, the August heat wave will persist across San Antonio and the surrounding region.

Residents should drink plenty of fluids, stay in air-conditioned rooms when possible, avoid prolonged exposure to the sun, and limit strenuous outdoor activities to the early morning or evening. Anyone working outdoors should take frequent breaks in shaded or air-conditioned areas and watch for signs of heat exhaustion or heat stroke. Heat stroke is a medical emergency.

IS THERE ANY BREAK IN SIGHT FROM THE HEAT?

While the upper-level ridge may shift toward Arizona by Thursday or Friday, offering a slight chance for isolated showers or thunderstorms, rain probabilities remain low. Consequently, any precipitation is unlikely to provide a significant or lasting reprieve from the ongoing heat.