As it is surrounded on all sides by the waters of Southern California, Catalina Island enjoys moderate Mediterranean weather year-round. The Alaska Current from the north provides a cooling effect in the summer, while the island’s subtropical geographic location ensures that it remains warm during the winter. The average summer temperature is 75°F (22°C), and the average winter temperature is only 10°F (5°C) cooler. With such uniform temperatures, there is really no bad time to visit. Of course, the beaches are more crowded during the summer, but fog or rain are more likely during the winter months, so it is really a matter of personal preference and convenience.

Avalon also enjoys a great deal of sunshine, over 250 days a year. Rainfall, at 14in (35cm) per year, is higher than that of nearby Los Angeles, but still low enough to make the region semi-arid, which means that humidity and mugginess are not a problem during the summer. Also unlike Los Angeles, Catalina Island has such aggressive conservation stances that there is minimal air pollution most of the time, even with nearby large cities.

Light, casual clothing is appropriate almost year-round, though a sweater or jacket is recommended, if for no other purpose than the channel crossing (where the winds can make the ride uncomfortably cool).