The forecast was for scattered showers as a wintry cold front moved over the Bay Area and then broke up. While the afternoon saw upper-teens to maybe 2o clearing winds.
But the actual winds barely reached the upper-teens at some sites and the Waddell did not even reach the mid-teens forecast.
This satellite animation shows the problem.
Notice the well organized cold front in most of the images as is slides over the Bay Area.
Then in the last frames notice how the cold front breaks up and then stalls over the Bay. This stopped the WNW clearing winds from fully reaching many sites.