FXUS66 KMTR 121140
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
440 AM PDT Thu Mar 12 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 225 AM PDT Thu Mar 12 2026

 - Well above normal temperatures through the forecast period

 - Widespread minor HeatRisk through Saturday, areas of moderate 
   HeatRisk Sunday through Wednesday

&&

.SHORT TERM...
Issued at 225 AM PDT Thu Mar 12 2026
(Today through Saturday)

Temperatures around 15 degrees above normal are expected today as 
the region is on the eastern periphery of upper-level shortwave 
ridging across the Eastern Pacific Ocean. Fortunately the location 
of the ridge will maintain onshore flow which will keep things 
comfortable at night and temperatures from running away. The only 
record high in jeopardy today is SJC with a maximum temperature 
forecast of 81 degrees which would tie the record from 2007. A 
passing upper-level shortwave trough to the north will tamp down the 
ridge and reinforce onshore flow, pressing pause on the warming 
trend Friday into Saturday. Of most impact in the short term will be 
minor HeatRisk. To mitigate your risk: increase hydration with 
water, reduce time spent outdoors or stay in the shade when the sun 
is strongest, and open windows at night and use fans to bring cooler 
air inside buildings. With roughly 50% of our population not having 
air conditioning, it is going to be essential that all preparations 
are taken to keep places of residence as temperature controlled as 
possible. Examples include turning your blinds upwards and closing 
them during the day, ensuring ceiling fan direction is 
counterclockwise, and keeping windows open at night to take 
advantage of the natural air conditioning that is onshore flow.

&&

.LONG TERM...
Issued at 225 AM PDT Thu Mar 12 2026
(Sunday through Wednesday)

Global ensemble clusters are in agreement that an anomalously high 
amplitude upper-level longwave ridge will begin to move into the 
region from the Eastern Pacific Ocean Sunday. As the aforementioned 
ridge encroaches our area, winds will veer to become northerly which 
will further warm and dry the region as the sea breeze circulation 
is turned off. The axis of the ridge is expected to be overhead on 
Tuesday, which will yield the hottest day of the forecast period, 
before slowly drifting into the Colorado River Valley. While beyond 
the official seven day forecast, there is uncertainty in the 
evolution of the ridge. Even with the uncertainty, global ensemble 
clusters illustrate that it is likely that we will be dealing with 
anomalously high heights through Friday of next week. We will be in 
record breaking territory Sunday through Wednesday not only for 
daily records, but monthly records too. Forecast record breaking 850 
mb temperatures and 500 mb heights are leading to a 50% probability 
that SJC reaches 90 degrees - this would be the first time ever in 
the month of March. It goes without saying that this is going to be 
the hottest that we have been this calendar year. Impacts wise, 
widespread minor HeatRisk on Saturday will give way to areas of 
moderate HeatRisk Sunday through Wednesday. To mitigate your risk: 
reduce time in the sun during the warmest part of the day, stay
hydrated with water, stay in a cool place during the heat of the
day, move outdoor activities to cooler times of the day, and for
those without a/c, use fans to keep air moving and open windows at
night.

&&

.AVIATION...
(12Z TAFS)
Issued at 434 AM PDT Thu Mar 12 2026

Current Oakland sounding shows rather dry low levels of the
atmosphere. This is further reflected on satellite imagery and 
sfc obs showing VFR conditions with mostly clear skies. Winds are 
light this morning and diurnally driven. Stronger onshore flow 
this afternoon and early this evening. VFR holds tonight, but 
35-50% chc of low cigs returning early Friday AM. VFR for tafs 
through the pd with some haze possible at HAF.

Vicinity of SFO...VFR. Light winds then onshore push this
afternoon with 10-12 kt.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. 

&&

.MARINE...
(Today through Tuesday)
Issued at 434 AM PDT Thu Mar 12 2026

Strong high pressure off the California coast will maintain
moderate to strong northerly breezes across the outer waters
through the weekend. Winds will eventually increase near shore
late Friday. The stronger winds will result in locally hazardous
condition.  Winds and seas ease into the next work week.

&&

.CLIMATE...
Issued at 1140 PM PDT Tue Mar 10 2026

The following are the record high temperatures at the long term
sites for March 12th, 15th, 16th and 17th.

Location         Mar 12      Mar 15      Mar 16      Mar 17

Santa Rosa       83 in 2007  88 in 2004  91 in 2004  87 in 1996
San Rafael       81 in 2007  83 in 1972  87 in 1972  84 in 1972
Kentfield        83 in 2005  85 in 2004  86 in 2004  87 in 1914
Napa             86 in 2005  86 in 2004  88 in 2004  92 in 1914
Richmond         81 in 2005  85 in 2004  84 in 1972  83 in 2004
Livermore        84 in 1916  83 in 1972  88 in 1972  87 in 1972
San Francisco    79 in 2007  82 in 2004  85 in 1914  85 in 1914
SFO Airport      77 in 2007  81 in 2004  82 in 2004  82 in 2004
Redwood City     83 in 2005  84 in 2004  84 in 2004  85 in 2004
Half Moon Bay    75 in 2014  74 in 1974  78 in 1972  83 in 2004
Oakland Museum   80 in 2007  85 in 2004  85 in 2004  85 in 2004
San Jose         81 in 2007  82 in 2004  85 in 1914  88 in 1914
Salinas Airport  83 in 2007  83 in 1972  87 in 2004  87 in 2004

&&

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

&&

$$

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

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Prepared by Boulder-Creek.com Weather at: Thu Mar 12 08:30:02 PDT 2026