A trough of low pressure swung thru The West overnight, this deepened the marine layer and allowed cooler air to progress much further inland. This was the reason temps dropped hard from the 106 in Paso Robles Monday to the 80s on Tuesday.
Near the coast, there were already marine clouds and marine influence in place and temperatures were only slightly cooler.
This mild air remains thru the rest of the workweek however high pressure builds again this weekend which will again compress the marine influence to the beaches and near coastal valleys. Inland valleys again warm to the mid-90s. The good news is that the second part of next week looks to cool again.
The weather pattern change is actually a concern at California fire sites, the increasing pace of the winds introduces concern on the leading edge of fires like the Caldor Fire threatening the Christmas Valley and the South Lake Tahoe area.