Thursday was the hottest day of the year so far in South Texas, with heat index values reaching over 110 degrees; a weak summer cold front is expected to approach South-Central Texas, but it will likely stall before moving through San Antonio, only slightly lowering temperatures.

Increased Storm and Flooding Risks

The stalled front will interact with the humid air, increasing storm chances over the next 24 to 36 hours; Isolated flooding is a possibility, especially late Friday into early Saturday. Morning showers and thunderstorms are expected across the Texas Hill Country, with the highest rain chances near 50% in areas like Kerrville, Fredericksburg, Junction, and Rocksprings. In San Antonio, the morning rain chance is less than 20%.

Afternoon rain chances in San Antonio will increase slightly, but storms are expected to remain scattered, leaving many areas dry; Temperatures are expected to reach 92 degrees, with heat index values peaking between 105 and 110 degrees.

Peak Storm Risk at Night

The greatest risk of storms is expected late Friday night, generally after 9 p.m., continuing into the overnight hours; During this time, a potential cluster of storms is expected to develop to the west and move slowly eastward. San Antonio storm chances are around 50%, with some storms potentially producing torrential downpours and damaging winds.

The Weather Channel provided additional details in German, forecasting temperatures of up to 32°C with a 100% chance of rain — Overnight, the temperature is expected to drop to 24°C, with a 50% chance of rain and humidity at 83%. Sunday is expected to bring partly cloudy conditions with a high of 34°C and a 24% chance of rain.

Market Predictions and Weather Impact

While not directly related to the immediate weather event, Coinbase has a prediction market offering related to San Antonio’s lowest temperature on June 18, 2026. This market is set to close on June 19, 2026, at 6 a.m. GMT+0. The market is available for trading but comes with warnings about the risks involved, including the possibility of total investment loss.

San Antonio residents are advised to monitor weather updates as conditions can change quickly. Authorities are urging preparedness for potential flooding, especially during the late-night storm cluster. Residents are encouraged to avoid unnecessary travel and to stay informed through local weather channels.