Many of us come from places where sailing is definitely a seasonal activity. Sailors in Michigan learn that boats don’t sail well in ice, for instance.
On San Francisco Bay, however, we enjoy year-round sailing. The Bay takes on a different mood in the winter which is characterized by predominantly gentle breezes and less fog.In the winter months, the Valley never gets very hot, so the Bay winds tend to be much lighter. You see less coastal fog because the seabreeze seldom blows. The fog we do get in the winter is usually associated with calms and is called Convection or Tule Fog.
Because the winds are lighter and air drier, you will find some of the best sailing days of the year in the wintertime. Keep a close eye to the weather, though. When winter storms arrive and depart we can see very strong winds. The approach of a storm is identified by a backing wind (counter-clockwise shift, as from west to south) and high cirrus clouds that get thicker and lower as time progresses. If you pay attention to these signs, you will have a warning time of 1 to 3 days. As the storm passes and the sky clears, you may experience strong westerlies.
Rain is rarely a problem for sailors. Most sailing areas in the world experience occasional rain and even thunderstorms throughout their sailing season. In the Bay Area, we usually have rain only during the winter. Of course, it is important to wear proper clothing (foul weather gear, hat, gloves, etc.), but don’t be discouraged from sailing just because mother nature turned on the fresh water shower. In fact, you will find that during the daytime, the Central Bay experiences much less rainfall than surrounding areas. This is due to the temperature/humidity difference on the water and the ‘fanning out’ of the clouds after they clear the coastal mountains. You will often finds that you can sail from Berkeley to Treasure Island or Alcatraz in partly cloudy conditions while watching rain fall on the rest of the Bay Area.
For us, wintertime sailing on the Central Bay conjures up visions of huge flocks of migratory birds, double rainbows (all the way!) over the East Bay hills and the camaraderie of sharing hot drinks with good friends as the boat glides effortlessly on a gentle reach. The many moods of SFBay sailing is one of its greatest attractions.