Hot conditions with heat illness concerns will continue for the interior through Sunday, while night through morning low clouds and fog will affect the coast and lower valleys. Temperatures will cool early next week with an expanding marine layer and gusty onshore winds. Some warming is forecast by late next week.
Another day of above normal temperatures for most of the area before things cool down for a while starting Monday. The coastal stratus has generally behaved Saturday and is hugging the beaches. Overall sunny skies and well above average temperatures continue, especially for areas away from the coast
The upper high which has had a stronghold on much of the southwestern U.S. this past week begins to break down some on Sunday. The weakening high in addition to a weak upper level trough that develops to our west on Sunday will lower heights, bring cooler temperatures (most noticeable inland areas), and increase the onshore flow. Monday brings additional cooling away from the coast as the upper trough swings into California and continues Tuesday as the trough pretty much stays in place. By Tuesday all but the deserts will have temperatures below normal, especially in northern San Luis Obispo County where highs are expected to be 10 to 20 degrees below normal by then. Also in the short term will be a slightly deeper marine layer each day and a repeat each night and morning of low clouds and fog.
Upper level trough persists over California on Wednesday. This will allow for some slight additional cooling and make Wednesday the coolest day of the 7 day forecast. Then on Thursday a weak shortwave dives southward from the Pacific northwest into the parent trough to develop a closed upper low situated just to our west by Friday. The marine layer depth should gradually reduce from Thursday through Saturday, although still deep enough for night to morning low clouds along most coastal areas. The one exception will be along the Santa Barbara South Coast were offshore gradients increase to help keep it clear overnight. Whatever nighttime stratus forms should be quick to clear out fairly quickly, especially Friday and Saturday.
Looking at the extended forecast there is a chance for another heat wave starting next weekend.