Microclimes in the SF Bay

One of the first things you’ll hear of moving to the SF Bay Area is about the microclimates of the various neighborhoods. Take your pick! You may choose to live where it’s 55F or 105F on July 4th….in the midst (or mist) of fog or where the sun shines full most days…..where the wind howls or where you’re fairly well protected from our invisible friend.

The SF Bay itself is no different. Some areas are quite warm while others are cool. The winds vary. The could be light and airy in one region and surprisingly near gale in another relatively close by. A wind shadow one day is a surprising arena of gusts the next. The “slot” may be dominant one day and it may be quiescent the next or it may be a double whammy with high winds from the north and a slot wind of 25-30 kn. And, of course, the waves vary with the wind, too. On top of all of this, the currents run faster in deeper waters and at different times and speeds depending on your location given the way tides affect our local water flow. The bottom line is that, when sailing on the SF Bay one must be alert and open to the possibility that things may change in a hurry and that no two days of sailing will be alike. One has to build a database of sorts, derived from a lot of sailing during which one is keenly observing, as to how the conditions may be in the different regions of the Bay and then draw upon the experience of sailing to adapt, adjust, and make way when conditions do change.

I had a rather interesting trek this summer that makes my point about the microclimes on the SF Bay. I had started in Redwood City and planned a sail to my home dock in Sausalito.

I planned my departure just before slack after high tide at about 12:30 in the afternoon. I did so as I wanted to take advantage of the ebb tide to carry me along toward my destination and cut the trip short by about 1.5 hours. there was no wind whatsoever in the harbor. I motored through the channel to the Redwood City port where the wind picked up. In fact, there were a couple of sailing vessel‘s tacking along in a northerly headwind making way toward the bay. Dredging activities were underway and there were two barges and one tug in the channel. I decided to motor at a safe distance behind the crisscrossing vessels. By the time I was in the bay, still about a mile south of the San Mateo bridge, the wind had become negligible. Well. It was under eight nights and I didn’t want to bother with my sails as I wanted to make good progress so I continued to motor.

A mile or so north of the San Mateo bridge the wind picked up to 12 knots. About the time that I decided to pull out my sails it had fallen to 5 knots. It seem to be coming from the west. The north wind had disappeared. It seemed the air temperature was 70 degrees. I continued to motor.

A mile south of the Bay Bridge the wind picked up to 13 knots from the Northwest. I’ve seen the wind dissipate in the area just north of the bridge through the wind shadow by the city so I decided not to put up the sails. Needless to say, I wasn’t yet sufficiently tempted!

My original plan was to enjoy my time on the water and to go to the east side of Alcatraz and Angel Island and then through Raccoon Straight. Interestingly, the wind from the north really picked up. I could see waves from the north and whitecaps off in the distance to the east of Angel Island. I thought about hoisting the sails and beating in it to make progress and to enjoy the remainder of my trip. I decided, however, that it was more important to make my destination in a timely fashion. So, I adjusted course to pass to the west of Alcatraz and to cross the Bay to Richardson Bay into Sausalito.

The wind picked up even more. At first, it was 18 knots from the north. As I passed the point of the city, thereby exposing my vessel to the west, nearing the slot, the wind shifted. Suddenly, it was 35 knots! From the west. The wind waves were three feet on top of an approximately five ft swell from the ocean. Maybe more.

Skiron cut through the waves and bounced up and down across some of them like a rocking horse. Water was everywhere. At times, it seemed the bow, was under water as the swells raced on deck toward me only to crash into the fiberglass dodger saturating everything. I was grateful for four things: the fiberglass dodger, that I was clipped and tethered to my vessel since I was single handling, that I had not raise the sails and didn’t have to try to feed or lower them, and that I’d seen this sort of weather in the ocean and had confidence in myself and the vessel.

I saw no way out other than to continue forward progress. I adjusted course to motor through taking the waves at about 30 degrees on the bow. Visibility was poor due to the waves crashing across the deck. I made a point of timing my “pop up” above the dodger to look for traffic, buoys, and to ensure that leeway would not push me into Alcatraz. I had the ebb in my favor in that regard though I suspected it was contributing to the breaking waves in the bay. It was such a wild bumpy stellar super fun ride! There was a fleeting thought of turning on the radar to assist with collision avoidance but I envisioned becoming injured while trying to go down stairs, an inability to alter the gain to not see the wave clutter, etc. Fortunately, I could see well enough every 15-20 seconds to know that I was safe. The highest wind I noted was 39 knots from about 285 degrees True. This part of the passage was cold. The air temperature was about 52 degrees.

The rollicking ride continued until I passed by yellow bluff where the wind and waves calmed down over a 2-3 min period. I still had waves. And, I was sensing the shift in the wind toward the north. It was 15 knots. No longer having to take wind and waves on the bow quarter I adjusted my course toward the Sausalito channel. The wind remained 15-18 knots until I pulled into my slip with the wind on the stern. It was sunny. The air temperature was 65 degrees.

The time of the trip was just over 4.5 hours. The microclimes in the Bay were quite obvious. Those of you used to sailing in the SF bay would probably recognize that the Northerly winds were on the back side of s low pressure system. In fact, a rare summer storm system had passed through. There was no rain. But, the winds, and the swell from the ocean, were certainly in keeping with the effects of the storm. The westerly wind across the slot was a result of the effects of heat in the Central Valley that drives our usual slot winds during summer. The ebb, of course, contributed to the height of the wind and swell waves to make the traverse all that much more memorable.

I managed to capture this short video just as conditions just started to deteriorate at the start of crossing the slot. They became much worse and precluded any further video out of concern for the possible demise of my iPhone in salt water. I had previously dropped one in a tide pool and witnessed its agonizing (and rather expensive) death. Notice the marked swing in height of the bow which is about four and a half feet off the water.

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