Salou has a Mediterranean climate with hot, dry summers and mild winters. The best time to visit is May through June, when temperatures sit in the low to mid twenties Celsius, the beaches are not yet packed, and accommodation is easier to find.
July and August are peak season -- temperatures reach the low thirties, the resort fills with Spanish and Northern European holidaymakers, and you will need to book well in advance. September and October are pleasant but bring occasional heavy downpours. Winter is quiet and mild, a good time to visit if you want to avoid crowds entirely.
Festivals
Salou has a full calendar of festivals. The Festa Major d'Hivern (winter festival) runs for two weeks in February with parades, dance groups, and street parties. The Golden Nights Summer Festival from late July to mid-August brings music and entertainment to the promenades. In September, the King Jaume Festival celebrates Salou's history, and in November the Salou Squid Festival is a highlight for food lovers. The Catalan Farmhouse hosts a traditional living nativity scene each December.