Hot weather this weekend with widespread Major Heat Risk. Elevated fire weather conditions for the Valley and foothills thru Monday. Abnormally warm temperatures are likely to persist into next week.
Skies are clear across the region. IR difference imagery shows stratus along the coast, but profilers indicate its quite shallow, especially north of the Golden Gate. Current temperatures are noticeably milder (around 3-8 degrees) compared to 24 hours ago and are mainly in the 60s and 70s in the mountains, and 70s to mid 80s in the valley and foothills. The Delta is the exception where Travis AFB is presently in the lower 60s with a weak Delta Breeze. Excessive heat remains ontrack through the weekend under strong high pressure.
Widespread moderate heat risk is expected with areas of extreme heat risk around the periphery of the Central Valley. Highs will be around 105 to 110 degrees through most of the valley, not quite as hot in the Delta where a weak breeze will hang on.
Overnight lows will also be very mild giving little or no relief, mainly in the 70s to lower 80s through much of the valley. This level of heat affects anyone without effective cooling and/or adequate hydration.
The ridge will begin to move eastward slightly on Sunday, but temperatures are expected to remain near Saturday’s highs. An Excessive Heat Warning remains in effect from late Saturday morning through Sunday evening for elevations below 4,500 feet, and a Heat Advisory for elevations above 4,500 feet.
Consider canceling outdoor activities during the heat of the day
Ensembles show the ridge axis shifting east as a trough moves into the Pacific Northwest on Monday, bringing some cooling to the region along with stronger onshore flow.
However, widespread Moderate Heat Risk is still expected as Valley and foothill highs reach into the upper 90s to around 106 degrees.
Monsoon moisture from the Desert SW is forecast to work its way northward around the periphery of the high Sunday into Monday before getting shunted east by the incoming trough.
A few thunderstorms may develop along and east of the Sierra crest, but activity will likely remain east of the crest given southwest flow.
Extended Discussion (Wednesday through Saturday)
Hotter weather likely to return later next week as upper troughing mid- week gives way to building high pressure from the Desert SW.
This will suppress coastal influence inland returning temperatures to above normal.