FXUS66 KMTR 010449
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
949 PM PDT Tue Mar 31 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1152 AM PDT Tue Mar 31 2026

 - Seasonably cool conditions with rain chances through Thursday

 - Above normal temperatures and offshore flow return Friday and 
   continue over the weekend

&&

.SHORT TERM...
Issued at 1152 AM PDT Tue Mar 31 2026
(This afternoon through Thursday morning)

It only took 29 days, but it's finally raining. A stationary front 
is offering an area of convergence for its tropical moisture tap. 
Rain shower activity will continue to drift south through the day as 
surface high pressure tries to nose in from the Eastern Pacific 
Ocean. A gale force low in the Gulf of Alaska will put a stop to 
that as it heads to the Washington/Canada border. The attendant cold 
front will bring us a winter-like feel with below normal 
temperatures, gusty conditions, and rain. Southwesterly winds will 
increase ahead of the cold front with northwesterly winds developing 
in the post-frontal environment. Widespread gusts of 20-30 mph can 
be expected with gusts up to 40 mph in the highest terrain. Rainfall 
totals are expected to be in the 0.10"-0.25" range with locally 
higher totals in the higher terrain of the North Bay and locally 
lower totals in the Interior Central Coast. Slick roadways can be 
expected due to the dry spell that has allowed oil to accumulate.

&&

.LONG TERM...
Issued at 1152 AM PDT Tue Mar 31 2026
(Thursday night through next Monday)

The pattern will quickly change Thursday afternoon as upper-level 
shortwave ridging noses in from the Eastern Pacific Ocean. The short 
wavelength of the aforementioned trough and ridge will tighten the 
pressure gradient. Strong northerly winds will result, primarily 
affecting exposed areas like the higher terrain and marine 
environment. The SFO-WMC pressure gradient is expected to become 
negative Thursday night as the wavelength moves inland, resulting in 
offshore flow. At 5 AM Friday, the ECMWF Ensemble mean is 
forecasting the gradient to be -9.81 mb while the GEFS mean is 
forecasting the gradient to be -7.76 mb. The 2 mb discrepancy is due 
to the ECMWF Ensemble showing a stronger high and stronger low 
closer together than weaker features farther apart in the GEFS. This 
uncertainty is propagated through Friday and Saturday with the ECMWF 
Ensemble bottoming out at -10.96 mb at 5 AM Saturday while the GEFS 
is well on its relaxing trend at -5.24 mb. Nonetheless, a moderate 
offshore flow event can be expected Thursday night through the 
weekend with a 35 knot 925 millibar jet streak across the North Bay. 
This will translate to gusts of 40 to 50 mph in the higher terrain, 
namely the North Bay Interior Mountains, East Bay Hills, and Eastern 
Santa Clara Hills. The ridge will also send temperatures soaring 
back to well above normal.

&&

.AVIATION...
(06Z TAFS)
Issued at 939 PM PDT Tue Mar 31 2026

VFR is expected to prevail until early Wednesday morning in the 
wake of scattered showers across our area earlier today. One
exception is KAPC that is already MVFR and is expected to remain
so through the forecast period. KSTS will follow suit later during
the overnight hours. 

Vicinity of SFO...Bay Area terminals are expected to be VFR until
later in the overnight hours when cigs drop to MVFR and are
expected to remain MVFR through the remainder of the forecast
period. Light rain will increase in coverage from late morning
through the afternoon hours with breezy southwest winds out ahead
of a cold front that arrives later Wednesday night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR is expected to prevail through the
forecast period with a chance of MVFR cigs in the hours
surrounding sunrise. There is a slight chance of light rain late
in the TAF period but confidence is too low for mention in the TAF
attm. 

&&

.MARINE...
(Tonight through next Monday)
Issued at 939 PM PDT Tue Mar 31 2026

Fresh to moderate southwesterly breezes tonight out ahead of a
cold front will become northwest behind the cold front as it
passes through our area late in the day Wednesday into the evening
hours. Strong northerly breezes will develop by Thursday
afternoon and persist through Friday with moderate seas building
to become rough with widespread hazardous conditions. Conditions
improve for the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM Wednesday to 3 AM PDT Friday for 
     Mry Bay-Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 
     10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 
     10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to 
     Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.

&&

$$

SHORT TERM...Sarment
LONG TERM....Sarment
AVIATION...JM
MARINE...JM

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Prepared by Boulder-Creek.com Weather at: Tue Mar 31 22:30:02 PDT 2026