FXUS66 KMTR 260548
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
948 PM PST Tue Nov 25 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 120 PM PST Tue Nov 25 2025

 - Dry and mild conditions continue through Thursday 

 - Cooler temperatures Friday and into the weekend as the next 
   system approaches

 - Gusty offshore winds are possible by the end of the weekend and 
   into early next week

&&

.UPDATE...
Issued at 851 PM PST Tue Nov 25 2025

And here we go again. Temps are falling to or near to the dewpoint
temp, which means that the relative humidity is at or approaching
100%, which means saturation yielding haze or fog. In addition,
the winds are very light. Looking at observations around the area
Santa Rosa is already reporting 2 SM, Napa 1.5 SM, and Livermore 5
SM. Will likely do a quick update to the forecast to expand the
fog farther west. Apart from that, the forecast remains on track
this evening.

&&

.SHORT TERM...
Issued at 120 PM PST Tue Nov 25 2025
(This evening through Wednesday)

Low clouds persist over the North Bay and East Bay, yet are forecast 
to begin clearing later this afternoon. However, if they do not, 
temperatures will be cooler than currently forecast by up to 10 
degrees. Elsewhere, temperatures are forecast to reach into the 60s 
across most inland areas while the immediate coastal areas of the 
North Bay and San Francisco Peninsula remain in the mid-to-upper 
50s. 

As offshore flow persist in the higher elevations across the region, 
the marine layer remains compressed. Thus, there is greater 
probability for less coverage of fog overnight. However, still 
expecting patchy to areas of dense fog across the North Bay valleys, 
East Bay valleys, and the Santa Clara Valley overnight. Temperatures 
overnight are forecast to be mostly in the 40s with the coldest 
interior spots potentially lowering into the upper 30s. 

As the ridge axis shifts eastward into southern California, 
temperatures will continue to warm on Wednesday. This is when we are 
expecting temperatures across the interior Central Coast, Santa Cruz 
area, southern Santa Clara and Hollister valleys, and far inland 
North Bay valleys to reach or exceed 70 degrees F. These 
temperatures will be up to 10 degrees above seasonal averages. 
Again, similar to today, areas that do not see afternoon sunshine 
will likely be a few to several degrees cooler. 

&&

.LONG TERM...
Issued at 120 PM PST Tue Nov 25 2025
(Wednesday night through next Monday)

On Thursday, an upper level trough is forecast to approach the 
Pacific Northwest brining unsettled weather to that area. Locally, 
we are forecast to see similar temperatures as Wednesday for daytime 
highs. By Friday, this feature will shift into the northern part of 
the Intermountain West, thus cooling temperatures to near seasonal 
averages as a weak, dry back door cold front sweeps across the Bay 
Area and Central Coast. A reinforcing trough will drop out of 
British Columbia and act as an inside slider setup as in drops 
southward across the Intermountain West. This would lead to gusty 
offshore winds across our region. However, exact details reamin 
difficult to pin down at this time as there remains uncertainty this 
far out. Be sure to check back and keep up-to-date with the latest 
forecast information. 

&&

.AVIATION...
(06Z TAFS)
Issued at 948 PM PST Tue Nov 25 2025

Fog is starting to make its way into the North Bay and East Bay. 
Confidence is moderate to high in fog impacting STS, APC, and LVK 
overnight, moderate confidence it will reach OAK, SJC, and SNS, and 
low confidence in fog reaching SFO, HAF, and MRY. STS and APC have 
already reported fog with cameras showing fog filling in across the 
East Bay. Current thinking is that if sites do start to develop fog, 
visibilities and ceiling heights will drop rapidly. Winds stay light 
and offshore overnight before becoming more northwesterly to 
northerly during the day. Light, offshore winds redevelop overnight 
with potential for fog to return again.

Vicinity of SFO...VFR through the TAF period. Confidence is low that 
fog will extend across the SF Bay tonight and reach SFO. Current 
thinking is that fog will not be as expansive tonight as it was last 
night with fog more limited to the North Bay and interior East Bay. 
Winds stay light and offshore overnight before moderate onshore 
winds return during the day. Winds weaken and shift offshore again 
overnight with guidance suggesting some potential for lower 
visibilities and ceilings tomorrow night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR at MRY, VFR potentially becoming IFR at 
SNS overnight. For MRY - fog is not expected to reach the terminal 
tonight with winds remaining light and generally offshore through 
the TAF period. For SNS - leaned on persistence to show fog 
potential for tomorrow morning. The key thing to watch for is if fog 
will fill in across the southern Salinas Valley and gradually flow 
south to north. SNS looks to develop moderate SE drainage winds 
early tomorrow morning which could help bring fog northwards towards 
the airport. If fog does not develop in the southern portions of the 
valley, drainage winds could keep the atmosphere too well mixed to 
allow for fog formation at SNS. 

&&

.MARINE...
(Tonight through next Monday)
Issued at 948 PM PST Tue Nov 25 2025

High pressure over off the California Coast will maintain gentle
to moderate northerly conditions through mid week. Patchy dense
fog will be possible again tonight, especially in the bays. Seas
will continue to subside through Wednesday. Winds will begin to
increase again late week, building moderate to rough seas.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Dense Fog Advisory until 11 AM PST Wednesday for CAZ510.

PZ...None.
&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Kennedy
MARINE...BFG

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Prepared by Boulder-Creek.com Weather at: Wed Nov 26 00:30:02 PST 2025