Weather
Here are some useful links to help you prepare for your trip:
San Diego enjoys relatively mild winters and balmy summers. The late summer and early fall months from August through October are invariably the best, while the late winter and spring (February to April) are the least predictable. In May and June, morning fog usually yields to sun by midday, and in the height of winter, from December to January, the weather alternates between gloomy and delightful, as violent but short-lived storms pass in and out of the region. Even on the hottest of days, it's always a good idea to bring extra clothing in case you prolong your stay into the evening, or want a little protection from the sun and wind. Water temperatures range from the low 50s in winter to the low 70s in the summer.
Wind & Waves:
The most powerful storms come from Alaska in winter, bringing large northwest swells, variable north and west winds and some rain. In spring a mixed bag of medium-sized west swell with steady afternoon onshore winds is the norm. South swells arrive throughout the summer with the biggest and best ones coming toward the end. Local warming patterns called Santa Anas generate offshore breezes in the fall that bring fantasy days of warm, clear, dry conditions to the coast and groom the shape of the surf, while the global climatic condition called "El Niņo" (the child), can throw extreme conditions (both naughty and nice) at San Diego once or twice each decade.
Tides & Tide pools:
The tidal range in San Diego is relatively mellow, a maximum of about eight feet of change around the time of new and full moon phases. Still, on a flat or gently sloping beach, that can leave you high and dry or running for the hills in matter of hours. Knowing if the tide is rising can prevent you from a rude awakening as a set wave rushes in and soaks all your gear. A low tide will expose underwater reefs (especially around La Jolla and Bird Rock) and reveal a fascinating world of tidal plants and animals. Daily tides are usually posted at lifeguard towers and provided on phone and Internet surf reports.