A transition to cooler weather starts on Thursday
Our upper low is heading eastward, allowing for a nice Wednesday evening. With onshore flow, the marine layer will fill in a little better overnight in coastal areas, and could reach a few valley areas. Skies will clear slowly, but it should be mostly sunny by the afternoon, if not earlier.
On Thursday, our ridge of high pressure will flatten out, and a gradual cooldown will begin. Low temperatures will be in the 40s to low 50s. Highs will be in the mid to upper 60s, with a few interior valleys straggling in the low 70s. It will still be slightly above normal in most cases.
A large upper low will reach the eastern Pacific Ocean by Friday, with a broad trough extending southward. More mid and high-level clouds will drift across our region, in addition to a deep marine layer. Temperatures will decrease by another couple of degrees. Late Friday, there is a chance of light rain in San Luis Obispo County.
The front will move over our region on Saturday, bringing a 20 to 40 percent chance of light rain. There will be a second period of rain on Sunday. In total, preliminary models estimate at up to a quarter inch of rain for most areas, and up to a half inch for northwest SLO County. Snow levels will fall to around 4,500 feet.
On Monday, the trough will exit to the east and gusty winds will follow. We may see wind alerts triggered, particularly in Santa Barbara County. A ridge of high pressure will begin a slow warmup trend. Winds will weaken by Tuesday and skies will be partly cloudy.
