San Antonio Weather Brings Dangerous Heat and Flash Flood Threats Through the Weekend

San Antonio faces a dual weather threat this weekend as an intense heatwave combines with heavy thunderstorms and flash flood warnings. The National Weather Service has issued a Heat Advisory with peak heat indices between 108 and 112 degrees, while scattered storms bring the potential for locally heavy rainfall that could trigger flooding across the region through Saturday morning.

Dangerous Heat and Flood Risk Converge

The heatwave is driving hazardous conditions across South-Central Texas, with the Heat Advisory in effect through Friday evening across the I-35 Corridor, Coastal Prairies, and Rio Grande Plains. However, the weather pattern is further complicated by an approaching system bringing significant rainfall. A Flash Flood Warning remains active, with some areas already recording 2.5 inches of rain. The National Weather Service has identified a level 2 of 4 risk for excessive rainfall, with the greatest threat occurring Friday through early Saturday across the majority of South-Central Texas.

Rainfall rates during the heaviest storms could exceed 2 inches per hour, creating the potential for rises on area creeks, streams, and rivers. The heavy rain is expected to initially impact the Edwards Plateau and Hill Country on Friday before expanding southward and eastward toward the Rio Grande Plains, I-35 Corridor, and Coastal Prairies later in the day. In San Antonio specifically, a 40 percent chance of showers and thunderstorms persists after 1 p.m., with mostly cloudy skies and highs in the mid-90s, though heat indexes could reach 106 degrees.

Weekend Outlook and Storm Activity

Rain chances remain consistent into Saturday as temperatures moderate slightly to the high 80s and low 90s, though heat indexes are expected to remain in the triple digits. Storm chances drop to 30 percent Saturday night into Sunday as drier air moves into the region. The official start of summer on Sunday is forecast to be mostly sunny with highs near 93 degrees. Beyond the weekend, the heat and humidity are expected to build again early next week with predominantly dry conditions. Residents are advised to exercise caution if traveling Saturday morning due to ongoing storm activity and to keep umbrellas handy for scattered pop-up showers throughout the day.