The National Weather Service in San Diego has indicated a gradual cooling trend for the upcoming week, with temperatures expected to fall below normal due to a looming low-pressure system. "A pretty cohesive low cloud deck is gradually approaching the coast," as stated in their early morning discussion. There are mixed signals regarding the coastal areas, with some anticipating cloudy skies and others sunshine at the break of dawn today. The forecast obtained by NWS San Diego mentions that "Today will be seasonably warm, down from yesterday as a cooling trend gets underway."
Looking ahead, the low-pressure trough descending from the Pacific Northwest will impact the state by Tuesday, bringing cooler air and strengthening onshore winds, especially in mountainous regions and adjacent desert slopes. Certainly bringing a change, "the marine layer will deepen and coastal cloud coverage will expand in time and space each day," according to the Area Forecast Discussion. This marks an increased presence of nocturnal low cloudiness extending beyond the coastal regions.
By midweek, the entire coastal basin is expected to be engulfed by cloud cover, with potential drizzle arising from the thickening cloud deck due to the cooler air aloft. "It might be time to dust off the jackets," the NWS San Diego suggests, as they predict temperatures to sink significantly by Thursday, "generally 10-15 degrees below normal inland, even as much as 20 degrees below normal in the mountains." Winds will also see a spike, particularly on Tuesday afternoon and evening, with gusts potentially reaching 50-60 mph in the most affected areas.
The cooling phase is anticipated to halt towards the weekend, as the trough begins to weaken, with a predicted slight uptick in temperature. Still, "forecast temps this weekend don't quite reach normal," the 7 Day Forecast for San Diego forecasts. Further out, as per the NWS San Diego, marine conditions seem stable except for northwest winds gusting near San Clemente Island on Monday and Tuesday, which may present some challenges. In the skies, aviation forecasts must be mindful of varying cloud bases throughout the county, particularly those along the coastline, with cloud cover expanding overnight.
