The best months for a visit are May to June and September to October. The sea is warm enough for swimming and diving, the crowds are absent, and the Kroumirie hills are green. July and August are hot and busy — the beach fills with Tunisian families and European package tourists, and accommodation prices rise sharply.
Winter is quiet and mild by northern European standards, but some beach facilities close. The hills are occasionally dramatic in winter light. The Jazz Festival, held each July, draws performers from across North Africa and Europe and is worth planning around if you enjoy that scene.