Spring (April to June) is the best time to visit Sanlúcar. The weather is warm but not scorching, the Doñana wetlands are full of migrating birds, and the town is not yet crowded. The Feria de la Manzanilla, held in late May or early June, is Sanlúcar's main festival — a week of drinking, dancing, and general merrymaking centred on the bodegas.
Summer is hot (often above 35°C) and busy, particularly in August when Spanish families fill the beach. The famous horse races on the beach take place in August, in two sessions a few weeks apart — spectacular if you can handle the heat and the crowds. Autumn is quieter and the weather stays pleasant until November. Winter is mild and nearly empty of tourists, which has its own appeal if you want the bodegas and the beach to yourself.