Much warmer conditions will return on Wednesday and especially Thursday as northeast winds develop. A sharp cooling trend will arrive on Friday and continue into the weekend with a chance of light showers at times. Gusty west to northwest winds are expected starting Friday and lasting through the weekend.
Big swings in the weather this week, going from near normal temps, to much above normal, to well below normal all in the span of about 4 days. Temperatures today generally ran cooler due to a slightly stronger onshore push, though despite this the marine layer clouds managed to dissipate more efficiently than yesterday. We're already seeing the groundwork being laid for a warmer day tomorrow as those gradients are starting to turn around now and by Wednesday morning are expected to be lightly offshore. This probably won't have a significant impact on the marine layer as we still expect to see low clouds redeveloping overnight across most of the coastal areas with a good chance of dense fog returning as well.
Clouds should clear out quickly tomorrow, especially along the Central Coast where northeast flow will start up sooner and help warm things up there. In fact, for that area Wednesday will likely be the warmest day of the week as the northeast flow will focus more into Ventura county Thursday and help push temps well into the 80s and even some 90s. Winds stronger and temps warmer for northern areas Wednesday and southern areas Thursday.
Then wave goodbye to those warm temps for quite awhile as a very cold upper low will drop south along the west coast Friday and usher in a much colder air mass that will stick around for the next several days. Forecast soundings show the marine layer rapidly spinning up Thursday night. Temperatures will drop 20-30 degrees from Thursday's highs and northwest winds will be quickly ramping up, starting north of Point Conception as early as Thursday night then spreading over the remainder of the area through Friday afternoon. Wind advisories will likely be needed for San Luis Obispo & Santa Barbara Counties at a minimum.
Two upper lows will swing through the area over the weekend, the first being Saturday morning and the second Sunday afternoon. This will keep it very cool through the weekend with varying amounts of clouds and rain chances. Still some uncertainty with the rain as the first upper low will move inland near the Oregon/California border Friday morning and move southeast with limited over water trajectory. It's cold enough though that it should be able to squeeze out some light precipitation at least north of Point Conception Saturday morning. The second one on Sunday drops due south out of Canada and right along the coastline so again limited over water trajectory but very cold so a light shower can't be ruled out just about anywhere, but likely minimal rain amounts (most areas probably a tenth or less) for the weekend.
The cold upper trough finally shifts east Monday but breezy north winds expected to continue, especially in the mountains. Some height rises will follow Monday and Tuesday leading to a slight warming trend but still below normal temperatures.