By Kevin Wallis
June Gloom. May Gray. Uninspiring terms that Southern California surfers and coastal residents are all too familiar with. For the uninitiated, low clouds or fog frequently blankets the SoCal coast in the spring and summer months. Along with a monochromatic sky, these events can drop the coastal temps 10 to 20 degrees below areas that are just a few miles inland, so you’ll want to keep a thicker suit handy. Beyond the temperature contrast at the beach and the crummy light for budding surf photographers, the June Gloom can also impact SoCal’s surf conditions. And it can extend into July.
June Gloom — The water and sky become one. Photo: Jeremiah Klein
A Marine Layer Production
The gray and gloom you see comes from a marine layer of low altitude stratiform clouds that form in the offshore coastal waters. Think flat instead of fluffy clouds or single-ply instead of Charmin. A similar set up that produces our coastal eddy also creates the marine layer events. And driven by the same systems, the two often go hand in hand — high pressure centered off of the U.S. West Coast and a ‘thermal’ low pressure (from hot air rising in the desert) over the southwest U.S.
The air within the high pressure warms as it descends (subsides or sinks) toward the earth’s surface. That warm air eventually meets the cool, moist air above the Pacific Ocean. Typically, air temps decrease as we climb higher in altitude (think of snow on a mountain peak and green fields at the base) but this case is different. An inversion layer develops for a portion of the atmosphere where the temps are actually warmer at height than they are at the surface. This warm, very stable air mass above the moist Pacific air eventually cools, forming clouds as the air reaches its saturation point.
Voila! That’s how you make May Gray and June Gloom. And when sea surface temps are still quite cool in late spring, this pattern can last for days or even weeks at a time.
The National Weather Service breaks down the marine layer.
Where the Wind Blows
Obviously, onshore westerly wind isn’t the ideal conditions for the vast majority of surf spots in Southern California. But generally speaking, it’s that large-scale, onshore westerly wind that pushes the marine clouds over the coast, and occasionally into more inland areas. The good news? This onshore wind tends to be light, even going variable, and generally stays below 10 knots. That means it typically won’t blow the surf out. Bring on the afternoon sessions and smaller crowds.
Although generally light, onshore wind and a bland sky make for uninspiring conditions. Sunny, clean surf is always going to beckon more than a gray, textured wave. However, it’s not all doom and gloom for SoCal surf. The marine layer is generally thickest around sunrise and around particularly strong events, you may see some morning sickness during the dawn patrol session. But decent conditions can persist into the afternoon. When the marine layer sticks around through the day and extends deep into the interior of the state, it can suppress the afternoon seabreeze, keeping any onshore wind light and manageable.
Want to know when that marine layer will move in? Your local area’s high-res wind model is a great tool — it gives you an hour-by-hour forecast so you decide whether it’s worth a surf in the morning or if you’ll want to wait until the afternoon.