^Cold and damp in the summer. As Mark Twain
(didn't) say, "The coldest winter I ever spent was a summer in San Francisco." Basically, the City never gets much warmer than the waters of the Pacific, and in summer the heat of the Central Valley causes onshore winds that bring 55-degree air, and afternoon fog, into the City from the west. Up on the 20th or 30th floor, there's no thermal mass or asphalt reradiation to help shelter you from that.
So the same situation folks in Museum Park have this time of year when the lake is still 50 degrees.