SAN DIEGO (FOX 5/KUSI) -- Dense fog returned to the beaches Thursday morning and reduced visibility for drivers at times. Most of the low cloud cover has cleared, but low clouds and fog are expected to move a little further inland Thursday evening.  The marine layer is also expected to make a comeback this weekend, deepening with stronger onshore flow.  For now, high presssure to the south is keeping warm conditions for valleys, mountains and deserts into the weekend. Beaches will get slightly cooler weather Friday, then warm again Saturday. A bigger cool down for all areas is on the way for early next week as a low pressure system from the PNW sags south into the Golden State.  Some inland areas could drop to 15 to 20 degrees cooler than normal.  Along with chillier conditions, increased cloud cover, gusty westerly winds and chances of patchy, light rain are also expected for Tuesday.