Richardson Bay Microclimate

Geography affects our weather | map and post by Richard Pavek

Richard Pavek (Yellow Ferry Harbor) has written an extensive research paper on the climate of our neighborhood and the tidal factors that affect this region. Over the next few weeks, we’ll publish his findings chapter by chapter. Here’s Chapter One:

For the first few days after I moved to the Yellow Ferry Harbor in May of 1978, I woke to sunshine announcing another hot day! It felt like summertime heaven! Unfortunately, that lasted only two weeks until I woke to find a blanket of fog that covered the sky until noon. Summertime was over! For nearly three months, a chilly morning fog lasted until noon. Eventually, I discovered that the morning fog extended only two miles up the highway to the Horse Hill-Tiburon Ridge and sunshine reigned north of it!

But that is not all that is unique about Richardson Bay! Hot, gusty afternoon winds bedevil Marin City and the Floating Home community in the afternoon, while just two miles to the south, the winds in downtown Sausalito have calmed, and the air is cool.

Afternoon temperatures around Richardson Bay are typically 12-15 degrees cooler than San Rafael, several miles to the north.

Worst of all, the local tide charts are unreliable; they may underpredict as much as ten inches and often mispredict the day of the highest tide during the month.

We live in a basin formed by a horseshoe-shaped ring of warm hills surrounding a cold bay. Early morning fog-laden southwesterly spring and summer winds sweep over the ridges and uplands, covering the western part of the ring with a fog blanket that dissipates as it flows down Sausalito’s sun-warmed hills, even as the sun directly warms Tiburon and Belvedere. By noon the fog usually decreases, and around the ring, the air warms in time for lunch.

Later in the afternoon, the Southwesterlies shift and become Westerlies. Then, dried by the sun, they come roaring across the headlands through the Tennessee Valley gap to swirl and bluster, bedeviling the Northern end of Sausalito and Marin City. But when the winds do not blow, Marin City’s flats and Sausalito’s Floating Homes often heat up to 90 or 100 degrees!

Finally, having lost the sun’s heat, the winds settle down at sunset. And so, we lucky residents of Richardson Bay retire to our televisions, or our favorite book of the moment, to relax. Just another day in Paradise—until the Big Rains come!