It's been some time since the area has had to be concerned about excessive heat. Tomorrow through Sunday those concerns will be upfront with temperatures either near or surpassing 100 degrees in the interior valleys of San Luis Obispo County.
This surge of heat will also include the Central Valley of California and most interior valleys statewide.
You'll notice the concerns do not include beaches or near coastal valleys. The reason for that is that there will still be an ample amount of marine influence holding temperatures near average.
The mechanism driving the heat will be a ridge of high pressure which replaces a trough of low pressure which is currently moving out of the area.
While the Thursday through Sunday heat will be on only Saturday and Sunday get the excessive heat watch. Even though Thursday and Friday are not covered in that watch I think with temperatures so close to 100 degrees people should be taking common sense precautions through the entire period Thursday through Sunday.
The ridge of high pressure driving the heat is weakened by a trough of low pressure in the Pacific Northwest early next week. This will deepen the marine influence again and cool both coastal areas and the interior.
July 4th looks to be a day that features a lot of 70s on the South Coast and Central Coast with beaches in the 60s and interior valleys likely in the 80s.
Due to a trough being in the region if clouds form it's likely the base of the clouds will be high enough to allow good visibility for public displays of fireworks. However, the marine layer is very fickle and this Outlook could change so please stay tuned for the fine details of the holiday forecast.
