621
FXUS66 KMTR 220355
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
855 PM PDT Fri Mar 21 2025

...New UPDATE, MARINE...

.SYNOPSIS...
Issued at 1201 PM PDT Fri Mar 21 2025

A warming trend this weekend will bring the highest temperatures
of the year for most of the Bay Area and Central Coast early next
week.

&&

.UPDATE...
Issued at 850 PM PDT Fri Mar 21 2025

Generally clear skies continue across the region with scattered
high clouds. Satellite imagery shows the system just off the
coast of northern California, which could bring some fringe
showers to the northern parts of Sonoma County overnight.
Otherwise, there`s not a lot of impactful weather to report, and
the forecast remains on track.

DialH

&&

.SHORT TERM...
(Today and tonight)
Issued at 1201 PM PDT Fri Mar 21 2025

While far northern California and the Pacific Northwest deal with
a cold front and steady precipitation today, the Bay Area will
stay dry. Outside of some mid-to-high clouds associated with the
northern system, relatively benign weather conditions are in
store through the rest of the day and into Saturday morning. A
high pressure system in the Eastern Pacific is supporting light to
gentle onshore flow and near normal temperatures.

&&

.LONG TERM...
(Saturday night through next Thursday)
Issued at 1201 PM PDT Fri Mar 21 2025

The pattern starts to change significantly Saturday night. A
ridge will build over the West Coast and become amplified through
Monday. This will usher in a warmer air mass. There is high
confidence that the 850 mb temperature will climb to around 15C,
which is roughly the 95th percentile for this time of year. As a
result, we are expecting the surface temperatures to climb above
normal by Sunday, and well above normal Monday-Tuesday. How much
above normal is the question. The forecast confidence is still
low for coastal temperatures, which are highly dependent on wind
direction. The current forecast suggests onshore winds Sunday will
gradually shift to offshore Monday as the ridge axis moves inland
and a coastal trough develops. This synoptic scale forcing will
be fighting the smaller scale influence of the sea breeze, which
will encourage cooler onshore flow. At this point it`s not clear
which forcing will dominate, and it`s likely that the temperatures
will climb quickly through mid-day under offshore winds and
quickly drop in the afternoon as the sea breeze takes over. Our
best guess at this time, is the temperatures will reach the upper-70s
along the coast and mid-80s inland. That would make it the
warmest day of the year for most locations, and it will be
noticeable change. With clear skies and light winds, Sunday -
Tuesday will a good stretch to spend some time outdoors, but
beware of the hazardous conditions described in the "Beaches"
section below. The sea breeze cooling, combined with clear skies
at night, will allow the minimum temperatures to drop to the upper
40s or low 50s at night, which will keep HeatRisk in the minor
category from Monday-Tuesday.

After the warm stretch, more mild temperatures return by the
middle of the week. There is a weak disturbance on Wednesday-
Thursday that could bring some light rain to the North Bay and
gusty winds regionally. Beyond the official forecast period, we
are starting to see signs of a potential atmospheric river early
the following week (March 31-April 1 time frame). The uncertainty
is incredibly high regarding timing and intensity, but this system
warrants our attention as some of the more bullish ensemble
members paint a picture that could bring significant impacts.

&&

.AVIATION...
(00Z TAFS)
Issued at 448 PM PDT Fri Mar 21 2025

VFR-MVFR for the 00z TAFs, onshore winds easing during the evening
and then redeveloping Saturday afternoon.

Vicinity of SFO...VFR. West wind gusting near 25 knots, wind easing
to 5 to 10 knots mid to late evening. West wind near 15 knots Saturday
afternoon and early evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Mainly onshore winds 10 to 15 knots
decreasing to light and variable winds tonight and Saturday morning.
Onshore winds redeveloping Saturday afternoon.

&&

.MARINE...
(Tonight through next Thursday)
Issued at 850 PM PDT Fri Mar 21 2025

Winds across the coastal waters will increase to a fresh to strong
NW breeze by Saturday night and persist through Sunday. The winds
will diminish slightly early next week as moderate long period
swell moves in from the NW.

&&

.BEACHES...
Issued at 1201 PM PDT Fri Mar 21 2025

Long period swell will arrive as early as Sunday, bringing an
increased risk for sneaker waves through Tuesday. While the swell
height will remain moderate (below 10 feet), the dominant period
will exceed 15 seconds from the NW. These conditions make sneaker
waves more likely, which can unexpectedly run-up the beach much
further than normal. With warm weather and good surfing
conditions, the exposure to this hazard will likely be higher than
normal with more people expected at the beach. The most important
thing is to be aware of this hazard and to never turn your back
on the ocean.

&&

.CLIMATE...
Issued at 410 PM PDT Fri Mar 21 2025

Record high temperatures at the long term stations for March 24th
and 25th.

Station          March 24th          March 25th

Santa Rosa       91F in 1926         88F in 1952
Kentfield        88F in 1926         84F in 1997, 1930
Napa             86F in 1926         85F in 1988, 1970
Richmond         78F in 1951         83F in 1952
Livermore        82F in 2022, 2014   82F in 1997
San Francisco    82F in 1926         83F in 1952
SFO Airport      78F in 1970         85F in 1952
Redwood City     83F in 1970         84F in 1952
Half Moon Bay    73F in 1941         72F in 1969, 1947
Oakland downtown 75F in 1997         80F in 1988
San Jose         84F in 1926         84F in 1930
Salinas Airport  84F in 1951         85F in 1988
King City        87F in 1951         87F in 1988, 1930

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm.

     Small Craft Advisory from 3 PM to 9 PM PDT Saturday for Mry Bay-
     Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-
     Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 AM PDT Sunday for Pt Pinos to Pt
     Piedras Blancas 0-10 nm.

     Small Craft Advisory from 3 PM Saturday to 3 AM PDT Sunday for
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60
     NM.

&&

$$

SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Canepa
MARINE...Canepa

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, X, and YouTube at:
www.facebook.com/nwsbayarea
x.com/nwsbayarea
www.youtube.com/nwsbayarea