PALM SPRINGS, Calif. (CNN) -- Former President George H.W. Bush was released Monday morning from a California hospital where he was treated for dehydration after fainting on a Palm Springs golf course, his chief of staff said.

He is "back to 100 percent" and is expected to make a previously scheduled speech Monday night in Los Angeles, Jean Becker said. Bush, 82, was taken to Eisenhower Medical Center in Rancho Mirage, Calif., on Sunday.

"It was simply a case where he was playing golf in 93 degree heat and he had a fainting spell," Becker told CNN. Southern California is experiencing record high temperatures in the 90s.

Bush regained consciousness before he arrived at the hospital, where he was held for observation overnight, she said. Becker said the former president was in Palm Springs visiting Lee Annenberg, widow of media magnate Walter Annenberg and president of the charitable Annenberg Foundation.

President Bush was informed about his father's ailment Sunday before leaving Colombia on his tour of Latin America, said White House spokesman Tony Snow, traveling with the president.

Bush called his father from Air Force One and "his father assured him he was OK," Snow said.