, 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.
(18z TAFS) Issued at 1125 AM PDT Fri Aug 21 2026
Currently have a mix of IFR to VFR ceilings due to patchy stratus across our region. VFR conditions are expected to prevail this afternoon into the early evening hours. HAF is an exception as they may have a couple hours of VFR scattered cloud decks in the early afternoon before shifting back to IFR ceilings. Moderate to fresh onshore breezes around 10 to 15 kt expected through the day and ease overnight. The marine layer returns this evening impacting coastal sites first before filling in over inland terminals. Low to medium confidence on the exact stratus arrival as it is dependent on where the upper level low sets up during the day. Currently, all TAF sites are expected to develop IFR to MVFR ceilings, with coastal sites having a high chance of dropping to LIFR in the overnight hours.
Vicinity of SFO, Stratus is beginning to mix out of the SF Bay as moderate onshore breezes increase. VFR through the afternoon with occasional gusts around 20-25 kt possible. Winds remain around 10 kt overnight. Medium confidence on the timing of IFR ceilings as they may arrive as early as sunset. The marine stratus is expected to linger until late Saturday morning.
SFO Bridge Approach, Ceilings that develop may not be as low as SFO and clear before SFO does. Otherwise, similar to SFO.
Monterey Bay Terminals, Stratus is receding to the coastline resulting in VFR conditions through the afternoon. Onshore winds will be diurnally driven this TAF period. The marine layer holds on strong as it returns with IFR ceilings this evening around 6-7 PM PDT. Medium confidence that ceilings will drop to LIFR overnight (OVC003-004), but there is still uncertainty regarding the exact timing and duration of LIFR conditions. If LIFR ceilings develop, they are likely to impact visibility and linger at the terminals through mid Saturday morning.
(today through Wednesday) Issued at 1125 AM PDT Fri Aug 21 2026
An upper level low pressure system situated off the west coast is resulting in moderate to fresh northwest breezes across the outer waters. Strong breezes with occasional near gale force gusts in the coastal jet regions of Point Reyes and Point Sur is expected. Widespread hazardous conditions to small crafts across the coastal and bay waters continue into Saturday with diurnal sea breezes. Wind driven seas remain slight to moderate through the weekend.
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 Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 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.
