Excessive heat watches have been upgraded to heat warnings for the interior valleys of the Central Coast with the addition of a heat advisory for the Santa Ynez valley.
The advisories are for Friday thru Monday but surge of subtropical moisture arrives overnight and some sprinkles/showers could even develop into Thursday morning. Clearly this is a big change in the weather pattern most will notice.
The new pattern will likely highly limit or remove the low cloud deck near the coast, this is a cooling influence for the beaches and coastal valleys so even those locations will see temps rise quite a bit over the next few days.
It is the interior valleys that will be under the most extreme conditions with highs 100-110 thru Monday and potentially thru much of next week as well. The extent of this heat wave is a concern for fire weather and for general health as well.
Start thinking about your cooling system and activities so you can avoid the impacts. Additionally overnight lows will also be higher due to humidity and just the amount of time it takes to radiate off these higher temperatures at night. High clouds also reflect heat back down to the surface at night.
The reason for the heatwave is a large dome of high pressure from the Desert Southwest that will move westward over the Central Coast through Tuesday of next week (if not longer). The record high on Sunday and Monday is 110 degrees for Paso Robles and on Tuesday it's 109 degrees set back in 1967. The coastal valleys will reach the low 90s, while the beaches will reach the 70s under mostly overcast skies.