This heat event has been in the forecast for almost two weeks. A ridge in the jet stream is peaking over The West over the next couple of days. The impact of this will be strong surface high pressure, this eliminates marine cooled air from making it far inland.
This also includes some coastal valleys, places like SLO could see temps surpass 90. These are the hardest temps to nail in a forecast like this.
We know inland temps should be 100-107, but coastal valleys could range from the mid-80s to upper 90s. Beaches will be in the 70s and lower 80s, with the Southcoast in the 70s and 80s. That all is for Friday, Saturday is a bit more complex.
Marine clouds look to linger just off the coast (though a few intersecting patches wouldn't surprise me). Marine clouds and marine layer are not entirely the same thing. You can have a marine layer (marine-influenced air) without the condensed clouds, and it looks like just a little of that will be around Friday.
Saturday will look the same from a cloud cover perspective, mostly clear BUT the marine influence looks to be deeper and beach and near-coastal valley temps look cooler but inland temperatures will see little to no chance and range from 100-107 again.
The bigger changes come Sunday when a trough of low pressure pushes thru The West and temps drop dramatically, but temporarily. By the middle of next week, 100+ is possible inland again.