Maratea is a summer town: most hotels, restaurants and beach concessions open from Easter through October and many close entirely in winter. July and August are hot and busy, especially around the festival of San Biagio in early May and the patron saint days in summer. June and September are the sweet spot — warm enough for swimming, the sea still calm, the crowds thinner.
The Festa di San Biagio in May is the main event of the local calendar, with processions winding up to the basilica on Monte San Biagio. Christmas brings a small but atmospheric crib display in the old town. Winter is mild but quiet; expect many shops and restaurants to be closed, with little reason to come unless you want to walk the coastal trails in solitude.