Warm end to August

High pressure aloft will persist through the weekend bringing continued warmer than normal temperatures across inland areas and a shallow marine layer. A heat advisory is in place for all of our mountains and San Luis Obispo County interior valleys with highs in the triple digits. A cool down is expected through next week with a deepening marine layer.

A broad area of high pressure will continue to dominate the weather across socal through Sunday. The main highlight for the next two days will be heat, particularly over the lower elevation mountains, valleys, and desert. There will be a couple degrees of warming away from the coast on Saturday, and potentially a few more on Sunday. The heat advisories in effect for the mountains, interior SLO county have been extended through 9PM Sunday. These areas will see temperatures rise into the upper 90s to near 105. Despite not being under any advisories, the other valley areas across the region will still be quite hot, with max temperatures in the 90s. Even though it is August and typically hot in these areas, it is still essential to remember to protect yourself from the heat by drinking plenty of water and avoiding strenuous outdoor activities.

Coastal areas will continue to feel a nice sea breeze which will keep temperatures more moderated. However, with onshore remaining weak, temperatures will be able to climb into the 80s away from the beaches. The marine layer will remain shallow through the weekend with stratus likely staying confined to the coast. Due to the shallow marine layer, coverage may only be patchy. Similar conditions are likely through the weekend.

The upper ridge breaks down on Monday as a trough over the Pacific northwest digs into California. As a result, heights will lower, flow will turn cyclonic, and onshore flow will increase. There will be a decent cool down of at least 3 to 6 degrees across the board. The marine layer will deepen and low clouds will likely cover all coastal areas.

The trough will keep digging into California through the middle of next week bringing continued cooling through Thursday. Temps will be about 5 to 10 degrees below normal by mid-week, with the warmest valley areas struggling to reach 90. The marine layer will deepen each day with stratus likely trickling into the coastal valleys. The main forecast challenge for next week will be if we receive any effects from tropical storm Nora as it tracks through Baja early next week. Current projections show that its future remnants will send deep sub-tropical moisture into portions of southeast California. At this point with the bulk of the moisture and the best steering flow remaining east of our region, the forecast will be kept dry. If this deep sub-tropical moisture does make it into the forecast area, all bets are off in respect to the marine layer stratus holding together as the mid level moisture generally makes for a chaotic low cloud regime. By Friday, the steering mid-level flow will start to shift back to a drier southwest flow and high temps should trend up a degree or two.