Palma has one of the most reliably pleasant climates in the western Mediterranean. Summers are hot and dry — July and August see temperatures around 30°C with almost no rain — but the city itself remains functional, unlike some resort destinations that effectively shut down when the tourists leave. Spring (April to June) and autumn (September to October) are the best months: warm enough for the beaches and the outdoor life, with smaller crowds and lower prices. October is particularly good, with sea temperatures still comfortable and the island beginning to empty.
Winter is mild and bright, with daytime temperatures rarely dropping below 10°C. Rain comes mostly between October and February. Palma in January is a different experience from the summer city — quieter, more local, the cafes full of Mallorcans rather than tourists — and for anyone interested in the architecture, the art, and the food rather than the beach, it is a perfectly good time to visit.
The Festes de Sant Sebastià in January is Palma's main civic festival: a week of outdoor concerts, bonfires in the streets, and general celebration in honour of the city's patron saint. It is worth timing a winter visit around.