Granada's best months are April, May, September, and October, when temperatures are comfortable for walking the hills and the city's outdoor life is at its most animated. The Alhambra tickets become harder to get from Easter through September — book weeks in advance for peak season.
Semana Santa (Holy Week, late March or April) brings extraordinary religious processions through the streets, with elaborate floats carrying sacred images accompanied by penitentes in robes. The atmosphere is genuinely moving and nothing like what visitors might expect.
Summer (July–August) is hot — frequently above 35°C — but manageable if you follow the local pattern of sightseeing in the morning and evening, resting in the afternoon. Winter is mild, and the Sierra Nevada ski slopes are accessible just 30 km away, making Granada the only city in Europe where you can feasibly ski in the morning and eat tapas at the beach by evening (the beach requires about 90 minutes by car).
The Granada International Jazz Festival in November and various flamenco festivals throughout the year are worth timing a trip around.