Los Angeles, California — Southern California is entering a noticeably cooler and cloudier stretch as a Pacific storm system replaces recent warm conditions, bringing lower temperatures, deepening fog, and periods of light rain through the end of the workweek.
Forecasters say the shift will be gradual but widespread, affecting coastal, valley, and inland areas before a drier and warmer pattern returns early next week.
Weather pattern shifts along the West Coast
According to the National Weather Service, a high-pressure ridge that helped drive warmer weather across Southern California is now weakening. In its place, an upstream trough is moving toward the California coastline.
This change is strengthening onshore flow, allowing cooler marine air to push inland and increasing cloud cover across much of the region.
“The breakdown of the ridge will allow cooler air and more moisture to spread inland,” forecasters said.
As a result, temperatures are expected to trend downward through Friday.
Marine layer deepens, fog expands inland
The strengthening onshore flow will also cause the marine layer to deepen, leading to areas of patchy dense fog, especially during nighttime and early morning hours.
Counties expected to see the most noticeable impacts include San Diego, Riverside, Orange, and San Bernardino, where clouds may linger well into the afternoon.
Drivers should be prepared for reduced visibility, particularly near the coast and in valley locations.
Light rain expected, heavier totals in the mountains
Rainfall associated with this system is expected to remain light overall, with most areas receiving 0.25 inches or less.
Forecasters say the highest rainfall totals will likely occur along south-facing mountain slopes, where amounts could reach up to 0.50 inches.
“This is not expected to be a significant rain event,” the National Weather Service noted, “but periods of light rain or drizzle are possible.”
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Snow levels are forecast to remain between 5,000 and 7,000 feet, limiting any accumulation to the highest mountain peaks and keeping lower-elevation travel routes unaffected.
Cooler temperatures settle in through Friday
As clouds increase and onshore winds strengthen, daytime highs will drop across Southern California.
By Friday, temperatures are expected to bottom out in the lower to mid-60s for most coastal and valley areas, a noticeable change from earlier in the week.
The combination of cloud cover, fog, and cooler air will make conditions feel especially gray and damp, even where rain totals remain minimal.
Timeline: How the weather unfolds
Here’s a look at what residents can expect over the coming days:
Wednesday through Friday:
A steady cooling trend continues with increasing cloud cover. Periods of light rain or drizzle are possible, along with patchy fog during mornings and overnight hours.
Friday night:
The storm system shifts south, ending most rain chances while cooler temperatures linger across the region.
Saturday through Sunday:
A gradual warming trend begins as high pressure slowly rebuilds over the West Coast. Skies begin to clear, and rain chances diminish.
Monday through Wednesday:
Drier offshore flow returns, bringing warmer temperatures and the potential for advisory-level Santa Ana winds, especially in Ventura and Los Angeles counties.
Santa Ana winds possible early next week
Looking ahead, forecasters say offshore winds could strengthen early next week, allowing temperatures to climb back to above-average levels, particularly in eastern Ventura County and western Los Angeles County.
The return of Santa Ana winds may bring gusty conditions, which could elevate fire weather concerns in typical wind-prone areas.
“Once offshore flow develops, conditions will dry out quickly,” forecasters said.
Drier pattern expected to last
Beyond the weekend, the overall outlook points to a drier weather pattern lasting through the end of the month. No major storm systems are currently expected after this one exits the region.
Residents are advised to remain cautious during periods of fog and light rain, especially during commutes, and to stay updated as forecasts are refined.
How is the cooler, gray weather affecting your plans this week? Share what you’re seeing in your area in the comments below.
