From the National Weather Service:

 10 Years Later…Remembering the Floods of June 30-July 6, 2002

June 2002 was a month of precipitation extremes, beginning very dry, but ending in the last five days with widespread heavy rain and extreme flooding that continued into early July. On Tuesday afternoon June 25th, scattered showers and thunderstorms formed over the eastern part of South Central Texas. In the early evening hours, these storms moved west and dissipated, bringing only spotty rains to parts of South Central Texas. The next day (June 26th) began hot, with temperatures rising to 99ºF at San Antonio, 103ºF at Del Rio, and 97ºF at Austin Camp Mabry and Austin Bergstrom. Showers and thunderstorms formed again in the afternoon and continued into the evening. Showers and thunderstorms continued to increase in coverage and intensity from the 27th through 29th.

The prior rainfall from the 26th through 29th preconditioned the soils, streams, and rivers to their water holding capacity, such that when heavy rains fell on June 30th and July 1st, significant flooding occurred. San Antonio International Airport received 9.52 inches of rain on July 1st, setting the record for that date, but also for the whole month of July. The previous July monthly record was 8.29 inches in 1990. Additional showers and thunderstorms continued July 2nd through 5th. Since the ground was already saturated, more flooding occurred. The heaviest rain fell over the Hill Country to the north and west of San Antonio. The upper level trough that focused the heavy rain over South Central Texas finally began to move north on the 6th and showers and thunderstorms tapered off to only scattered activity the 7th through 10th.

In total, 15.72 inches of rain fell in the first 10 days of July at San Antonio, with similar and even higher amounts at many other locations in the area. The final July 2002 total at San Antonio was 16.92 inches, making it the wettest July and the 2nd wettest month (after 18.07 inches in October 1998), for the period of record from 1871 to 2011. Austin Bergstrom picked up 3.56 inches and Austin Camp Mabry 4.39 inches in the first 10 days of July. The final rainfall for July 2002 at Austin Camp Mabry was 4.94 inches, while 5.32 inches fell at Austin Bergstrom. Meanwhile, Del Rio only had 0.15 inches of rain in the first 10 days of July 2002, with a monthly total of 0.87 inches. Maximum rainfall amounts of 30- 40 inches occurred between June 30th and July 6th over portions of Bexar, Kendall, Gillespie, Kerr, Bandera, Uvalde, and Medina counties.

Click here for incredible flood photos from the event.