Although the climate is mild, upper 40s to high 60s (about 8-20°C), with little variation in temperature year-round, the weather on the islands is always unpredictable. Winds of 30 mph can blow for days, or sometimes a fog bank will settle in and smother the islands for weeks at a time. Winter rains can turn island trails into mud baths. In general, plan on wind, lots of sun (bring sunscreen), cool nights, and the possibility of hot days. Water temperatures are in the 50s and 60s (teens Celsius) year-round. Also be aware that inclement weather or sea conditions can cause concessionaires to cancel trips on the day of the excursion, so it's a good idea to have a plan B just in case.
Avoiding the Crowds
Unlike many of the more popular (and more easily accessible) national parks, the Channel Islands rarely have a crowding problem. In a given year, about 300,000 people stop in at the park visitor center, but less than 100,000 set foot on the islands. Although visitors to any given island rarely number more than a few hundred a day, the open section of Anacapa (the closest and most popular day-trip destination) is so small that it may be difficult to completely separate yourself from the flock. As for the other four islands in the park, you should have no trouble finding a secluded picnic spot or overlook. Santa Barbara Island is the least crowded, Santa Rosa allows for backcountry beach camping, and San Miguel is the most remote (the boat trip takes 3-4 hr.) and the wildest.
January through March, gray whales can be viewed from the islands as they pass by on their annual 10,000-mile migration from their warmer breeding grounds off the coast of Baja California to their cold-water feeding grounds in the Arctic Ocean. Blue and humpback whales can be seen in the waters off the islands between June and October.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.