High thin clouds filtered the sun into
a glowing disk. The sun is also top-lighting
what must be a fog-bank on the Bay since it
obscures what would be a silhouette of San Francsico.

Followup:

I just heard on the news that it was caused by smoke from forest fires to our north in Oregon and Washington, and it is continuing even today.

Taken across SF Bay from Shoreline Park, Alameda