, Issued at 200 PM PDT Wed Aug 5 2026 (This evening through Thursday night)
While not as extreme as yesterday, today's 24 hour trend still indicates a downward trend of an additional 2 to 10 degrees. Persistent onshore flow and lurking marine layer led to additional cooling observed today. A welcomed relief for the interior to get a break before the next round of heat.
Tonight through Thursday night: Despite high pressure overhead the marine layer will continue to be the main driver of overall weather in the Bay Area and Central Coast broadly speaking. Clouds will move inland at night and clear back to the coast in the afternoon. Greatest impact of the marine layer will be near the coast/bays and lower elevations. Thermal belts remain active with the hills remains mild and dry through the short term. Thursday will once again feature a broad range of temps from the coast to the interior.
Onshore flow will also bring some breezy winds each afternoon/evening. Additionally, some high level smoke may lead to some haze.
..issued at 230 PM PDT Wed Aug 5 2026 (Friday through next Tuesday)
No significant changes for Friday through the weekend from previous forecast. The upper level ridge will flex again over the region bringing higher 500mb heights and even warmer 850mb temps. As a result of the large synoptic set up we'll see the following in response: compression of the marine layer, increase of temperatures through Saturday and then moderating on Sunday, increasing HeatRisk values to include Major, decreasing RH, and enhancement of the thermal belts. Less confident for a Heat Advisory across the interior on Friday, but very confident we'll need a Heat Advisory on Saturday. It's also possible that we may need one on Sunday as well since heat impacts are cumulative and we'll be day three of the warm up. Starting to sound like a broken record at this point, but the onshore flow/marine layer will keep the natural AC at the coast/bays. We'll see above normal temps, just not to critical levels. The upper level ridge eases its grip by Monday/Tuesday with subtle cooling as the heat shifts back toward the Central Valley.
One other item of note for the long term will be the influx of upper level moisture. Guidance still shows a solid push of high PWAT air from SoCal. The leading edge will nose in as early as Thursday, but the bulk of it will arrive Thursday night through through early Saturday. We do have some steep lapse rates aloft, but thankfully instability is somewhat lacking. Having the ridge in place helps. Really need to have a trigger for convection to be a concern, like being on the edge of the ridge with a shortwave trough or vort max. Therefore, expecting mainly cirrus at this point. Will continue to monitor regardless.
(00z TAFS) Issued at 424 PM PDT Wed Aug 5 2026
VFR at all terminals late this afternoon as the marine layer remains staged at the coastline awaiting a return as we head toward sunset. KOAK balloon measured ~1500ft marine layer. An offshore meso-low will help channel stratus through the Bay Area with widespread coverage expected by early morning Thursday across most of our area below 1500ft. However, despite the widespread coverage, compression back to the coastline should be complete by early afternoon.
Vicinity of SFO, VFR. Expect IFR/LIFR ceilings to develop shortly after sunset and persist through the late morning. The offshore Otter Eddy mentioned above will accelerate stratus through the Golden Gate and the Bay Area all the way into the Central Valley overnight with relatively light onshore flow at the surface but moderate lower boundary level flow (~975mb) driving the push inland. Expect VFR by late morning through the remainder of the forecast period.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, More typical diurnal pattern this far south with onset of IFR/LIFR before sunset and persisting through late morning to early afternoon, with VFR expected thereafter through the remainder of the forecast period.
(tonight through next Monday) Issued at 424 PM PDT Wed Aug 5 2026
Light to gentle breezes will persist through Thursday along with seas between 2-6 feet. Winds will begin to increase again out of the northwest going into Friday morning with building seas and hazardous conditions for small craft returning for the upcoming weekend.
Ca, None. PZ, None.
