July and August are the peak months. The weather is warm and dry by Galician standards — temperatures hover around 22–26°C — and the Ría de Arousa fills with sailboats. The Festa do Viño Albariño, held in the first week of August, is the event of the year: up to 40,000 people pour into the Praza de Fefiñáns for tastings from producers across the Rías Baixas denomination, live music, and the general atmosphere of a town that knows it is good at something. Book accommodation well in advance if you plan to attend.
May, June, and September are the best months for a quieter visit. The weather is pleasant, the restaurants are not overwhelmed, and you can actually stop and look at the Praza de Fefiñáns without navigating a crowd. Galicia gets significant rainfall from October through April — not torrential, but persistent — and the countryside turns a vivid green that justifies the region's nickname, the Spanish Ireland.
Winter is quiet and atmospheric. The manor houses and granite streets feel genuinely medieval in the low light, and you'll have the Santa Mariña de Dozo ruins more or less to yourself. Seafood is available year-round and arguably better value off-season.