San Diego rests on planet Earth in a subtropical climate belt, which translates into descending, dry and warm air currents. This warm, dry air descends on San Diego from above and warms the land around San Diego, but the cool wind from the Pacific Ocean causes offshore winds, and the contrast in temperature creates what's called an inversion layer. This is technically a fog, though when you look up, it often looks like clouds because it is so high. The colder the ocean temperature and the air is, or the greater the contrast in temperatures, the longer the marine layer will stay around. It’s typically very difficult to predict if and when the marine layer will be burned off by the sun. LA is only sunny 65% of June, and San Diego, a mere 58% of the month, but right along the beaches and coast, the percentage is actually much smaller.
So what is a triathlete to do, if he or she wants to go for a bike ride on a beautiful sunny day in San Diego? Go East. Drive or bike inland. At some point the fog will have lost its energy and the sun will shine. For years when training, I was looking for an up-to-the-moment way of discovering how far inland the marine layer extended when I set out on bike rides in San Diego – and last week, Matt Christopher from Elite Racing and the Competitor Group, Inc., sent me a link to the current satellite view of San Diego and the exact location of the marine layer. Now I don’t have to call Ramona’s smoothie shop and ask “Is it sunny there?” before deciding which way to ride. Here is the link to the current marine layer satellite view: Click here. Bookmark it! Train smart and safe!