Late spring (May to June) and early autumn (September to October) are the sweet spot, with warm sea, hot but not extreme days and thinner crowds. July and August are hot, busy and pricey, softened by sea breezes, while winter is mild but quiet, with many resort businesses and some sites on reduced hours or closed.
Summer sun is strong and many sites like Kamiros, the Acropolis of Lindos and the Old Town walls offer little shade. Carry water, wear a hat and sunscreen, and plan the most exposed sights for the cooler morning or late afternoon.
The island's western and southern tips, especially around Prasonisi, can be windy with strong currents that suit surfers more than casual swimmers. Check conditions and flags, swim at organised beaches, and take care entering the water over rocks.
Many visitors rent scooters, ATVs or cars, and accidents on unfamiliar coastal roads are the most common cause of injury. Wear the helmet, drive within your experience, avoid riding after drinking, and watch for gravel on bends and fast local traffic.