Day's mother, Dening, told the Gold Coast Bulletin today that the golfer's uncle and six cousins also died in the typhoon, which has killed nearly 4,000 people and left more than a thousand missing.
Day is playing in the World Cup of Golf starting Thursday at Royal Melbourne on Australia's team with Adam Scott.
Day's mother, who migrated from the Philippines to Australia 30 years ago, told the newspaper "my daughter has been updating him, but I don't want to bother him because he has commitments."