, Issued at 1017 PM PDT Thu Aug 20 2026 (Friday and Friday night)
Improved onshore flow in the lower boundary layer especially for the North Bay and Bay Area should result in more extensive stratus intrusion overnight coinciding with overnight lows closer to normal for this time of year. Warm and dry conditions will continue both overnight and through the day above 1000ft inland and near the coast, this includes in vicinity of the Timber Fire where relatively light winds continue to be a mitigating factor. Some elevated convection earlier Thursday night has tapered off or now in the steering flow of the ridge. Any mid/upper level moisture attempting to reach the Central Coast would be greeted by anemic instability and confluent flow aloft.
As the closed portion of the upper level low responsible for the persistent troughing recently will slowly approach the Oregon coast later tonight with a steady fetch of onshore flow continuing across our area, with only a marginal increase in depth of the marine layer expected into early Saturday morning.
..issued at 1017 PM PDT Thu Aug 20 2026 (Saturday through next Thursday)
The parent low mentioned above moves onshore into the PacNwest during the day Saturday with a weak troughing pattern lingering offshore at our latitude through at least the weekend. However, the persistent ridging over the Desert Southwest will shift east as well during this time , thus we'll continue to see the cooling trend through the weekend into the beginning of next week. There's a weak signal for the ridging to the east to build back toward the west coast by the middle of next week, which would bring warmer temperatures, but at that point a potential tropical system well to our southwest may add noise to the NWP.
(12z TAFS) Issued at 437 AM PDT Fri Aug 21 2026
Currently LIFR-VFR. Flight conditions will continue to deteriorate through the morning; however, current flight categories should prevail. With IFR stratus retreating to the coast this afternoon, VFR is expected for all terminals except HAF. Relatively lower confidence in the return of stratus tonight due to an increase in wind and guidance/models showing clearing upstream this evening. Nonetheless, the forecast leaned on persistence and the resilience of the marine layer. Diurnal winds will prevail.
Vicinity of SFO, Currently IFR with southwesterly flow. High confidence in VFR by this afternoon. Moderate confidence on an IFR ceiling returning tonight. Diurnal winds will prevail.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, Currently LIFR with northwesterly flow at MRY and LIFR with westerly flow at SNS. Fog has recently developed at MRY; therefore, there is low to moderate confidence that it'll reach SNS as the worst conditions are at the immediate coast. IFR stratus will stick close to the coast this afternoon with another return to LIFR conditions this evening. Diurnal winds will prevail.
(today through Wednesday) Issued at 437 AM PDT Fri Aug 21 2026
Widespread hazardous conditions are expected with the diurnal sea breeze Friday and Saturday. Moderate to fresh northwesterly breezes will prevail with locally strong breezes across the coastal jet regions of Point Reyes and Point Sur. Slight to moderate seas will prevail.
Ca, None. PZ, Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Mry Bay-SF Bay N of Bay Bridge.
Small Craft Advisory until 3 AM PDT Saturday for Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm.
Small Craft Advisory from 9 AM this morning to 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0- 10 nm.
Small Craft Advisory from 3 PM this afternoon to 3 AM PDT Saturday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM.
