I live in Northern CA and not far enough inland to be the Central Valley, but it was hot today. The forecast was for high 70s, but the car thermometer read 90 in the shade. First day of air conditioning for us.
In the summer/fall we usually get one or two weeks of 100s. (maybe 3). In SF, the fog makes it much cooler. For every mile you go east from SF you gain a degree, so 60 in SF is 87 where we live.