Hot conditions with heat illness concerns will continue away from the coast through the weekend, especially through Saturday. Low clouds and dense fog will continue over the coast through the weekend. Cooling expected next week with a return to normal conditions and an expanding marine layer by mid-week. Gusty onshore winds will affect interior areas each afternoon. A warming trend is likely for the end of next week.
The upper level high that brought all the heat this week, is currently centered over Arizona, and will move very little through Sunday. Meanwhile a weak upper level low, currently centered 1000 miles southwest of Los Angeles, will slide to the north and into northern California through Monday, and deepen some along the way. This all adds up to hot conditions continuing over the interior, with little change through Saturday, then slight cooling on Sunday as the low approaches, and more noticeable cooling Monday as the low also pushes the high to the east. As such, triple-digit highs and warm lows leading to excessive heat warnings will continue through Saturday for the interior areas.
Over the coastal areas, near normal temperatures will prevail as the shallow marine layer that developed this morning will persist through Saturday with little change. Low clouds and dense fog will also be common Saturday morning. As the upper level high starts to lose its grip over the region, along with strengthening onshore flow, the marine layer should expand some Sunday and Monday. This will bring more low clouds and cooling to coastal valley areas.
The weak upper level low that will usher in the cooling trend Sunday and Monday, will slowly move through California and continue the downward trend in temperatures Tuesday and Wednesday, focused over the valleys and mountains. The rest of next week is a little uncertain, but the general trend is warmer.