FXUS66 KMTR 061642
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
942 AM PDT Tue Oct 6 2026

...New UPDATE, MARINE...

.KEY MESSAGES...
Updated at 155 AM PDT Tue Oct 6 2026

 - Hazardous heat inland persist through Thursday, never leave 
   children or pets in unattended vehicles!

 - Elevated fire weather conditions persist in the interior
   through Thursday

 - Coastal flooding concerns due to astronomical tides and 
   thermal expansion through the weekend
 
 - Hazardous beach conditions along Pacific coastline later this 
   week into the weekend due to long period swell

&&

.UPDATE...
Issued at 939 AM PDT Tue Oct 6 2026

Patches of fog linger at the immediate coast, but the widespread
dense fog has retreated with solar heating and the Dense Fog 
Advisory has been allowed to expire. Have lowered today's and
Wednesday's high temperatures at the immediate coast with the 
upcoming forecast update to address the blend running warmer than
the observations, which will be expanded upon in the forthcoming
full AFD update. 

DialH

&&

.SHORT TERM...
Issued at 155 AM PDT Tue Oct 6 2026
(Today and tonight)

A shallow and compressed marine layer confined to the coast most of 
Monday afternoon has made some slight progress inland over the 
Russian River Valley, city of San Francisco and Monterey Bay into
the Salinas Valley into the overnight hours. The low 
ceilings/patchy fog may limit visibility down to 1/2mi or less 
overnight into early Tuesday morning. The ridging pattern over our
area will continue to be reinforced today and tonight in the wake
of the weak disturbance that shifted east yesterday. Moderate 
HeatRisk continues to be the primary concern in the short term 
forecast along with elevated fire weather conditions, especially 
for higher elevation locations due to hot and dry conditions.

Follow these tips to avoid heat exhaustion and heatstroke:

* Stay hydrated and drink plenty of fluids.
* Wear lightweight, light-colored clothing.
* Reduce time spent outdoors or stay in the shade.
* Never leave people or pets unattended in vehicles.
* Use sunscreen if going to the coast or the pool.

&&

.LONG TERM...
Issued at 155 AM PDT Tue Oct 6 2026
(Wednesday through Monday)

Wednesday and Thursday will see similar temperatures as today, 
however improved onshore flow developing during the day on Thursday 
will mark the beginning of a return to more normal or slightly 
below normal temperatures for Friday into the weekend. Another 
weak upper level disturbance will develop offshore similar to this
past weekend, however its fate appears to be a merger with the 
remnants of Rachel. While Rachel and that disturbance merge, a 
more potent trough embedded in the Polar Jet will lift Rachel's 
remnants into the desert southwest while providing us with a 
potential 'inside slider'. Whether the energy associated with the 
Polar Jet increases onshore flow (deterministic GFS) or an inside
slider (deterministic ECMWF), we're going to see dry and gusty 
winds develop over the weekend potentially increasing fire 
weather concerns, with the inside slider scenario possibly leading
to another warm- up. The gusty winds over the East Bay may 
approach wind advisory levels Saturday morning albeit at high 
elevations. Unfortunately we continue to be dry through the 
extended forecast.

&&

.AVIATION...
(12Z TAFS)
Issued at 434 AM PDT Tue Oct 6 2026

Currently LIFR-VFR. Subsidence aloft is supporting a compressed 
marine layer that is too shallow to penetrate inland, leading to 
high confidence in VFR prevailing for bayshore and interior 
terminals. It's also bringing dense fog along the coast with high 
confidence in LIFR conditions continuing through 15Z for the coastal 
terminals of HAF, MRY, and SNS. Conditions will improve by late-
morning with LIFR stratus potentially lingering off the coast this 
afternoon. Dry air upstream is leading to uncertainty as it cleared 
stratus earlier, but now stratus is reforming. It's not expected to 
impact this morning's forecast, but it is leading to lower 
confidence (40%) in the return of LIFR conditions to coastal 
terminals tonight. Diurnal winds will prevail.

Vicinity of SFO...Currently VFR with westerly flow. High confidence 
in VFR and diurnal winds prevailing.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Currently LIFR and calm at both terminals. 
High confidence in LIFR conditions in the form of dense fog 
prevailing through 15Z. Conditions will improve through mid-to-late 
morning with VFR expected by 18Z. Diurnal winds will prevail. Low to 
moderate confidence on LIFR conditions returning tonight due to dry 
air upstream and light offshore flow overnight.

&&

.MARINE...
(Today through Sunday)
Issued at 939 AM PDT Tue Oct 6 2026

High pressure off the Pacific Northwest Coast and low pressure
near Southern California will maintain gentle to moderate
northerly breezes through Thursday. Northerly breezes will then
increase strong to very strong Friday into Saturday, bringing
widespread hazardous conditions for small craft. Frequent gale
force gusts are likely across the northern waters during this
time. Moderate seas will prevail through Thursday, building to
become rough to very rough Friday into Saturday.

&&

.FIRE WEATHER...
Issued at 456 AM PDT Tue Oct 6 2026

Maximum and minimum temperatures 10 to 20 degrees above normal
across the interior with a compressed marine layer at the coast 
will persist through Thursday. Widespread poor minimum relative 
humidity is expected across the interior with little-to-no 
recovery for the higher terrain. Active thermal belting and prolonged
burn periods will continue across the higher terrain. Winds 
remain the limiting factor, with diurnal winds prevailing except
for light northerly/offshore flow overnight across the higher
terrain. ERC values are forecast to reach near records during the
next seven days from the hot and dry conditions. An inside slider
like pattern succeeding this heat event will likely keep elevated
fire weather conditions around. 

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 10 PM PDT Thursday for CAZ503-504-506-508-
     510-512>518.

     Coastal Flood Advisory until 1 PM PDT Thursday for CAZ506.

PZ...None.
&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Sarment
MARINE...MM

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Prepared by Boulder-Creek.com Weather at: Tue Oct 6 10:30:03 PDT 2026