@jeffhaas, I’m also in the SF Bay Area (south bay), and have found that the OpenWeatherMap forecast for Cupertino, Sunnyvale, and Los Altos simply reeks. It’s garbage; apparently OpenWeatherMap can’t handle the Bay Area’s microclimates. In my case, Monte Sereno is a reasonable approximation; certainly better than the forecasts for the cities I list above. I suggest you try nearby cities and zip codes; I had to go through half a dozen before I found one that worked.
It’s too bad that we’re stuck with a service that produces such crap, but that’s the way it is. Hope this helps.