I can only speak about Sacramento.  Not only is it hotter, but we also have far more marine layer making it our way each year now, and a lot more humidity.  We are seeing a lot more thunderstorm activity in the Sierra's and has reached all the way down into the valley.  The weather change is so pronounced that practically anyone I have spoken to notices and acknowledges it.  We have had a real nasty heat wave with lots of humidity, and now it is unseasonally cooler.  I have lived here for 34 years.  
In the early sixties I lived in Tracy, CA, not far from Sacramento but away from major heat islands. At that time it was common for summer temperatures not to dip below 105 degrees at night for three or four days at a time, temps in the tomato fields routinely went up into the 120s, and the humidity was sickeningly bad (from all the irrigation canals, it was claimed). I seriously doubt that this summer is worse than that of 1961 or 1962, but of course, it isn't over until the fat lady sighs and dies.
Lived in Bakersfield til '55. Same experience.
Hey,  I'm still alive and kickin!