The Costa Blanca has one of the sunniest climates in Europe, with mild winters and hot, dry summers. Altea is pleasant year-round, though each season has its character.
May, June, and September are the sweet spots — warm enough for swimming, not yet at peak crowd density, and still cool enough in the evenings to sit out comfortably. July and August are hot (often above 35°C) and busy with Spanish and northern European visitors; the old quarter gets crowded in the middle of the day but quietens pleasantly in the late afternoon.
Winter is mild by northern European standards — daytime temperatures of 15–18°C are common, and the town empties of tourists and fills with retired expats. The light in winter is extraordinary, soft and clear, and the seafood restaurants are less frantic. Christmas markets and local festivals make December worth considering.
The Moros y Cristianos festival in late July is Altea's most spectacular local event — parades, costumes, and mock battles re-enacting the town's medieval history.