SAN ANTONIO – The 500-year flood – we saw that on October 17, 1998.

Thursday marks the 26th anniversary of the devastating weather event, which resulted in 31 deaths and $1.19 million in damages.

Put simply, a “500-year flood” describes the likelihood that a massive flood will occur.

Rain began to fall overnight and by Saturday morning, October 17, 1998, major flooding had already occurred across much of the area. Watch archived aerial footage from Sky 12 in the video player above.

But that was just the beginning – 11.26 inches of rain officially fell in the Alamo City that day, ending up with more than 15 inches.

Read former KSAT meteorologist Mike Osterhage’s first-hand account of the flood at this link.

Watch: Flood ’98: KSAT’s complete video documentary on the 1998 South Texas flood