His chief of staff says Sunday's celebration is low-key and Bush is spending the day with his wife, Barbara Bush, and other family members in Kennebunkport. His son, former president George W Bush, is in town. The family is planning a private dinner.
Chief of Staff Jean Becker says the family patriarch is doing well after a scare last summer when he broke a bone in his neck in a fall at his home. Bush has celebrated previous birthdays by skydiving, his latest jump when he turned 90.
A Republican, he served two terms as Ronald Reagan's vice president before being elected president in 1988.