These temperatures are for Anacapa. Typically San Miguel is five degrees cooler. Air temperature runs 60 to 75 in the summer and fall and in the fifties in the winter and spring. Visibility rarely goes below 10 feet and can be as high as 100 feet. The average is 40 feet and on most days the bottom is visible from the boat.
Weather is so localized and changes so much it is impossible to give an accurate overview.
The islands offer protection so even on windy days there is usually a calm spot. Check just before the trip, remember that TV weather is not telling much about the real conditions at the islands, and that in California the word storm can mean light drizzle with 10 knot winds. Also keep in mind that it can be windy the day before the trip and be flat calm the next morning. Divemasters do not take divers on tours. They give briefings, answer questions, and are ready to offer assistance.