I´ve spent 6 weeks in cumbuco dec-jan some 3 years ago.
Place is epic on the days with a more or less constant 20knots breeze. Alot of space to surf in the atlantic, but seriously crowded in the small flatwater lagoons. Nights are laidback and easygoing, some bars on the beachfront and plenty of restaurants . If your looking for more fun, just head in to Fortaleza where you probably find more than you are looking for. Windseason ends in late January, so any time before that is good.