FXUS66 KMTR 200537
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1037 PM PDT Tue May 19 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 1036 PM PDT Tue May 19 2026

 - Diurnally driven winds, with onshore winds during the afternoon 
   and early evening.  

 - Above normal temperatures continue through midweek with seasonal 
   temperatures returning late week.

 - Warm and dry weather through Thursday leads to elevated fire
   weather concerns for the interior Bay Area and Central Coast. 

&&

.SHORT TERM...
Issued at 1036 PM PDT Tue May 19 2026
(Tonight through Thursday)

Little change in the forecast as high pressure slowly creeps into 
Northern California today. Satellite imagery this evening shows 
high clouds sliding down the West Coast, with much of the Bay Area
likely seeing some cirrus. With the current data, temperatures 
look to be on track; however, if we're not able to get radiational 
cooling, our temperatures for tonight might be low/cool. This 
would be because the clouds act as blanket, allowing less heat to 
escape at night. It'll be something to keep an eye on over the 
next few hours. 

In terms of Wednesday, if you guessed, "No pattern change. Ha, this 
means another day of warmer weather", you'd be correct! A potential 
fly in the ointment is if the marine layer attempts to manifest 
around 500 feet. This might keep temperatures a few degrees cooler 
along the immediate coast, but elsewhere temperatures should be 
similar to Tuesday, perhaps a few degrees higher. 

&&

.LONG TERM...
Issued at 1036 PM PDT Tue May 19 2026
(Thursday night through next Tuesday)

No major changes to the extended forecast. Upper level troughing 
looks to keep hold over the western US, while the Pacific high 
pushes even more into northern California on Thursday. With the high 
being a bit more pronounced, another warm day will be on tap. 
After that, guidance has flow becoming quasi-zonal for a brief 
period before troughing returns on Friday. The marine layer looks 
to be around 500ft on Thursday, deepening to around 1000ft by 
Friday and then lasting through the weekend. With onshore flow, a 
deeper marine layer, and troughing through the weekend the NBM's 
temperatures are bit too warm. Opted to start trending towards 
slightly cooler temperatures given the ensembles and cluster 
analysis. But there is a chance ridging wins out and temperatures 
might warmer. Definitely something to keep an eye on over the next
few days.

&&

.AVIATION...
(06Z TAFS)
Issued at 926 PM PDT Tue May 19 2026

Currently VFR at all terminals with the exception of MVFR at HAF.
Winds may become calm and/or light and variable overnight. Low to
moderate confidence in IFR conditions developing at terminals 
tonight - the most likely timeframe is 12Z to 16Z. Coastal 
terminals will be at greatest risk with risk decreasing for 
bayshore and interior terminals, respectively. Higher confidence 
in IFR conditions returning tomorrow night.

Vicinity of SFO...Currently VFR with northwesterly flow. Moderate
to high confidence in VFR and diurnal winds prevailing through 
the TAF period. Low probability for sub-VFR conditions to develop 
at the terminal tonight as the compressed marine layer will be 
unable to penetrate the San Bruno Gap. Reasonable worst case 
scenario is stratus sneaks through the Golden Gate Gap and brings 
FEW/SCT to the north side of the terminal.

SFO Bridge Approach...The San Mateo Bridge Approach has a lower 
probability of sub-VFR conditions.

Monterey Bay Terminals...Currently VFR and calm at MRY and VFR with
northerly flow at SNS. Confidence has increased in sub-VFR
conditions developing at the terminals tonight, especially for
MRY. Ceilings will likely be on the cusp of IFR/LIFR.

&&

.MARINE...
(Tonight through next Monday)
Issued at 926 PM PDT Tue May 19 2026

Hazardous conditions for small craft will continue through
Wednesday for the northern outers due to rough seas and strong
northerly breezes. Elsewhere, moderate to fresh northwesterly
breezes and moderate seas will prevail. Conditions improve into
the weekend as seas and northwesterly breezes become moderate.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 PM PDT Thursday for Pt Arena to Pt 
     Reyes 10-60 NM.

&&

$$

SHORT TERM...KR
LONG TERM....KR
AVIATION...Sarment
MARINE...Sarment

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Prepared by Boulder-Creek.com Weather at: Wed May 20 04:30:03 PDT 2026