The National Weather Service in San Diego reports a cooler weekend ahead for Southern California, with temperatures expected to dip below average. Today's highs are anticipated to range from the lower to mid 70s near the coast to as high as 103 in the lower deserts. Cooler temperatures will persist into Sunday morning, reaching lows mainly in the 50s/low 60s for coastal and valley areas and 70s for the deserts, temperatures around 5-10 degrees below their usual marks for this time of the year.
As winds continue to sweep across the desert mountain slopes into the deserts, they'll pick up again this afternoon and into the evening, creating breezy conditions, particularly through passes and favored areas, where gusts may reach 35-45 mph, and locally up to 50 mph as noted by a more detailed forecast discussion provided by the National Weather Service. The cooling effect is partly due to an upper-level low sweeping in from the Pacific Northwest, and with the trough's progression, temperatures will rise slightly on Sunday. However, they will remain below normal for this time of year.
Beginning Sunday and stretching into next week, a gradual warming trend is expected, though minor day-to-day temperature variations will persist through the end of the week. However, high temperatures will remain a couple of degrees below normal by Tuesday despite the warming trend, according to the National Weather Service. While marine layers will become shallower through early to mid next week, low cloud coverage is predicted to be patchy at best again on Sunday morning.
In terms of precipitation, while the monsoon moisture is expected to return by Thursday and Friday, thunderstorm probabilities are currently below 15 percent. The potential for thunderstorms remains low even with an uptick in precipitable water anticipated in the midweek forecast, with weather models showing quite a bit of variability. Breezy northwest winds may reach up to 20 knots Saturday afternoon in the maritime areas, although the National Weather Service does not anticipate any hazardous marine conditions through Wednesday. Skies are expected to remain clear in the mountains and deserts, apart from gusts that could touch 40 knots through the San Gorgonio Pass, possibly affecting visibility and causing moderate up/downdrafts near the mountains into the early night.
The National Weather Service does not currently request Skywarn activation. However, it encourages weather spotters to report significant conditions should they arise. For aviators, visibility is anticipated to remain unrestricted, with mostly clear skies in the mountains and desert areas, with some exceptions due to localized wind gusts.
