An upper level ridge has begun to build into Northern California, bringing a warming airmass to the region. Very little in the way of stratus is being detected up along the California coast early this morning, and onshore flow is light through the Delta. As such, temperatures across the forecast area are running 5 to 10 degrees warmer than 24 hours ago.
High pressure will remain in control across the region today and into Sunday. Look for high temperatures to reach the mid 90s to lower 100s across the Valley both days this weekend, with 70s to90s over the mountains. These forecast high temperatures are roughly 10 to 15 degrees warmer than normal for this time of year.
A modest cooling trend is expected starting on Monday as a series of shortwave troughs move through the Pacific Northwest. This should enhance onshore flow through the Delta, bringing more substantial cooling in that region. Look for temperatures to remain a few degrees above normal Monday into Tuesday.
Extended discussion (Wednesday through Saturday)
West-southwest flow aloft expected to predominate later next week as the upper ridge shifts east into the Rockies and a weak trough develops along the West Coast. Pattern is dry for interior NorCal with deeper moisture and instability further to the north and east. Temperatures expected to be close to average with onshore flow through the Delta.