High pressure has developed over The West which has reduced the depth of the marine layer. This doesn’t allow the cooler and dense air from the coast to get inland which allows high temps to hit the triple digits. Highs in the interior valleys of SLO county will likely stay near 100-105 for 3 more days before seasonal temperatures return.
But at the coast onshore winds will keep high temperatures in the coastal valleys in the low to mid 80s, while most beaches will be in the low 60s, but SW facing beaches will be in the lower 70s.
Saturday night into early next week the ridge flattens and allows for more depth to the marine layer for cooler temps but I wouldn’t call the change dramatic. The pattern looks warm inland with cool at the beaches into the end of the month.