São João Festival (June 23-24): Porto's biggest celebration honoring Saint John the Baptist. The city erupts in festivities with street parties, live music, traditional dances, fireworks, and midnight display over Douro River. Locals playfully hit each other with plastic hammers and leeks. Traditional grilled sardines eaten throughout the night. Cascading barbecues line Avenida dos Aliados. Absolutely unmissable if visiting in June, but book accommodations months ahead.
Festa de São João do Porto (entire June): Month-long celebrations leading up to São João night with concerts, street markets, exhibitions, and cultural events throughout the city.
Serralves em Festa (late May/early June): 40-hour non-stop contemporary arts festival at Serralves Foundation with music, dance, theater, visual arts, workshops, and performances. Over 200 activities attract 200,000+ visitors. Park open all night with special illumination.
Fantasporto (February-March): International Film Festival specializing in fantasy, horror, and sci-fi cinema. One of world's oldest fantasy film festivals, attracting filmmakers and fans globally.
NOS Primavera Sound (June): Major indie and alternative music festival in Parque da Cidade featuring international and Portuguese artists. Multi-day event with multiple stages.
Queima das Fitas (early May): Porto University student celebration marking end of academic year with parades, concerts, and festivities. Colorful ribbons (fitas) burned in ceremonial tradition.
Matosinhos Jazz Festival (late October): Weekend jazz festival featuring Portuguese and international jazz musicians in venues around Matosinhos.
Planning note: Many shops, restaurants, and some attractions close on public holidays. Museums often closed Mondays. Plan accordingly and book restaurants ahead during festivals.