Guadalupe River Basin Rainfall Update and Weekend Forecast

Heavy rainfall caused flooding in the Guadalupe River basin between July 16 and July 17, 2026, according to the National Weather Service (NWS) Austin/San Antonio. The weather event centered on rain that fell late Wednesday and into early Thursday, leaving the region to prepare for a shift in weather patterns heading into the weekend of July 19.

The San Antonio Express-News reports that a major weather pattern shift is expected to follow these floods. While the NWS Austin/San Antonio confirmed the timing and location of the heaviest precipitation in the Guadalupe River basin, the region is now transitioning out of the immediate flood threat as it moves toward Saturday, July 19.

Guadalupe River Basin Rainfall Timing

Data from the NWS Austin/San Antonio indicates the bulk of the precipitation occurred in a concentrated window. The most significant rainfall hit the Guadalupe River basin starting late July 16 and continuing through the early hours of July 17, 2026.

This timing created immediate runoff challenges for the basin. The concentration of rain over a short period is a primary driver of flash flooding in Texas river systems, where saturated soils can quickly lead to rising water levels.

Forecast and Weather Pattern Shift

Following the flooding events, the San Antonio Express-News reports that the region is facing a significant change in its weather pattern. This shift follows the period of instability that brought the heavy rains to the basin.

The NWS Austin/San Antonio weekend forecast includes projections for Saturday, July 19. This transition follows the peak rainfall period that ended on July 17, moving the region away from the immediate flood-producing system.