This is an archived article and the information in the article may be outdated. Please look at the time stamp on the story to see when it was last updated.

Dear Tom,
A record rain hit Alvin, Texas, in the late ’70s? What caused so much rain?
— Richard Smith,
Dear Richard,
The 43-inch deluge that swamped Alvin, Texas, on July 25-26, 1979, still stands as the heaviest 24-hour rainfall in the U.S. The rain actually fell in just a 10-hour period from 9 p.m. July 25 through 7 a.m. July 26. Alvin, located near the Texas coast south of Houston, was the recipient of torrential rains associated with slow-moving Tropical Storm Claudette.
That rainfall is dwarfed by the world record of 73.62 inches that fell at Cilaos on Reunion Island, east of Madagascar, on March 15-16, 1952.
For comparison, the Illinois record 24-hour rainfall is 16.94 inches recorded at Aurora on July 17-18, 1996, while Chicago’s 24-hour record rainfall is 9.35 inches on Aug. 13-14, 1987.