Place the rice in a medium bowl. Drizzle warm water over rice; mash rice with a fork until almost smooth. Stir in baking powder, salt, and nutmeg. Lightly spoon flour into dry measuring cups; level with a knife. Gradually add flour and eggs to rice mixture, stirring with a whisk until well-blended.
Heat oil in a large skillet over medium heat. Drop rice mixture by level tablespoonfuls into pan. Cook 4 minutes on each side or until golden. Remove fritters from pan with a slotted spoon. Pat dry with paper towels. Sprinkle with powdered sugar. Serve immediately.