Onshore flow will aid in the development of the coastal marine layer Thursday morning, and while most of the cloud cover will mix out in other regions, some beaches could stay partly cloudy through the afternoon. The cloudy skies will linger along the north coast and be more patchy over west-facing beaches like Pismo Beach Thursday afternoon.
A different scenario will continue to pan out over the inland valleys as high pressure continues to build. An excessive heat warning will go into effect Friday morning through Monday night for the interiors across much of the central and northern portions of the state. The warning has been upgraded from a watch, indicating that excessive heat will impact the forecast. As a result, the community should expect daytime highs to range from the low 100s up to 110 degrees across the inland valleys, particularly while the excessive heat warning is in place.
Along the coast, daytime highs will stay closer to the upper 60s and upper 70s, with cooler conditions along the north coast. By the weekend, temperatures along the coast will increase a few degrees, and peak temperatures could reach the low 80s. The coastal valley communities will stay between the low to upper 70s Thursday, however, the weekend could bring temperatures in the upper 80s.