FXUS66 KMTR 192333
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
433 PM PDT Thu Mar 19 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 1247 PM PDT Wed Mar 18 2026
- Early season, long duration heat wave continues to bring
record- breaking temperatures and Moderate HeatRisk through
Friday
- Elevated potential for grass fires through the week due to
warm and dry conditions with periods of moderate offshore winds
- Gradual cooling trend begins this weekend
&&
.SHORT TERM...
Issued at 105 PM PDT Thu Mar 19 2026
(This evening through Friday)
Definitely a day of nuanced details and micro-climates around the
Bay Area and Central Coast. In the big picture it's still hot
around the region with temperatures well above for late March. The
details however show many locations are running colder than
yesterday and some of these locations will fall short of their
forecast high temperature. The shallow marine layer from early
this morning was enough to cause havoc on max temps with any
marine influence. All that being said, did tweak a few
temperatures this afternoon, but didn't completely give up on hope
for a warm up. A quick shift of the wind direction could allow
for a late day bump in temps. The airmass does support it as the
OAK sounding was 19.55C at 850mb at 12Z this am.
For tonight through Friday...marine layer from this morning has
faded and pretty much dissipated per satellite. Offshore flow is
gradually developing just above the surface. This will persist
overnight and actually strengthen a bit leading to better mixing
and some drying flow in the BL. Hi-res guidance shows this as well
with lower moisture at the surface. Some patchy clouds are
possible near the coast, but thinking less than last night.
Friday will be a transition day as the anomalously upper ridge
begins to slowly ease eastward. 500mb heights may decrease
slightly, but 850mb will likely reach their peak. As such, inland
areas have the potential of seeing some of their warmest temps
yet. Just like today however, coastal areas will be tricky again
with subtle temp differences due to marine influence late in the
day. Will keep Heat Advisory as is for now. Even if a few spots
near the coast/bays fall a little short of forecast highs heat
impacts are a cumulative effect.
&&
.LONG TERM...
Issued at 105 PM PDT Thu Mar 19 2026
(Friday night through next Wednesday)
The large area of high pressure continues its eastward push
Friday night into Saturday as an upstream trough/cold front moves
in. At the surface, local WRF model shows the rebuilding of the
marine layer Friday night. The cold front is expected to push
through day putting an end to the heat wave and bringing much
needed relief. The fropa will bring a 5 to 10 degree drop on
Saturday with an additionally 5 degrees on Sunday. Despite the
temp drop for Saturday and Sunday, temperatures will still be well
above normal for March. Temperatures moderate through the first
half of next week, but stay above normal with zonal flow over the
region. Previous forecast had precip brushing the N Bay around the
25th of March, but latest guidance continues with a drier
solution. If this chance of precip is looking less when does
confidence increase? Longer range ensemble forecast show a few
members producing rain around the beginning of April. As they say,
April showers bring May flowers. We'll see...
&&
.AVIATION...
(00Z TAFS)
Issued at 432 PM PDT Thu Mar 19 2026
VFR for most sites through the TAF period. Winds remain breezy
through the early evening before weakening overnight. WRF guidance
shows some potential for another shallow (250 ft) marine layer to
develop again tonight. The HREF signal is not quite as strong as it
was last night but coastal sites (HAF, MRY, potentially SNS) may see
patchy stratus development overnight. Onshore winds strengthen again
by late tomorrow morning with winds peaking between 10-15kt.
Vicinity of SFO...VFR. Winds are expected to shift onshore this
afternoon/evening before weakening and becoming variable/offshore
again overnight. LAMP guidance shows a low potential for low lying
clouds to develop tonight but confidence is low due to high pressure
suppressing the marine layer. Onshore winds strengthen to around 15
kts tomorrow afternoon/evening. Main change to the TAF was to push
back the return of onshore winds tomorrow to closer to 00Z as they
have been returning later than originally forecast.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Light, onshore winds continue through this
evening before winds shift offshore overnight. Low chance of stratus
developing at MRY overnight as a shallow marine layer attempts to
redevelop. HREF guidance shows a patch of stratus in the Monterey
Bay tonight but the cloud cover signal is not very widespread -
keeping confidence lower. Winds shift onshore again tomorrow
afternoon with breezier conditions expected at SNS.
&&
.MARINE...
(Tonight through next Tuesday)
Issued at 432 PM PDT Thu Mar 19 2026
A gentle to moderate breeze continues across the inner waters
with moderate north to northwest breezes over the outer waters.
Northwest winds will begin to increase tonight across the outer
waters before spreading across the inner waters Friday through
the weekend, with hazardous seas developing by Friday night in
response to the strengthening winds.
&&
.CLIMATE...
Issued at 421 AM PDT Wed Mar 18 2026
The following are the record high temperatures at the long term
sites for March 18th, 19th and 20th.
Location Mar 19 Mar 20
Santa Rosa 83 in 2004 84 in 2004
San Rafael 81 in 1964 82 in 1960
Kentfield 83 in 1996 82 in 2001
Napa 86 in 1914 86 in 2004
Richmond 80 in 1996 81 in 2004
Livermore 82 in 2015 87 in 1915
San Francisco 80 in 2010 78 in 2004
SFO Airport 78 in 2010 78 in 2004
Redwood City 81 in 2010 82 in 2004
Half Moon Bay 79 in 2010 75 in 2010
Oakland Museum 81 in 1984 78 in 2001
San Jose 82 in 1988 78 in 2004
Salinas Airport 87 in 1997 80 in 1934
The following are the record high temperatures at the long term
sites for the entire month of March.
Location
Santa Rosa 91 on March 16, 2004
San Rafael 88 on March 25, 1952
Kentfield 91 on March 28, 1923
Napa 92 on March 17, 1914
Richmond 88 on March 18, 2026
Livermore 90 on March 25 and 26, 2025
San Francisco 87 on March 11, 2005
SFO Airport 85 on March 25, 1952 and March 17, 2026
Redwood City 93 on March 17, 2026
Half Moon Bay 83 on March 31, 2000 and March 17, 2004
Oakland Museum 89 on March 17, 2026
San Jose 89 on March 14, 2015
Salinas Airport 93 on March 18, 2026
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Friday for CAZ006-502>506-508>510-
512>518-528>530.
PZ...Small Craft Advisory from 3 PM Friday to 9 AM PDT Saturday for
Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 9 PM this evening to 9 AM PDT Saturday
for Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...MM
LONG TERM....MM
AVIATION...Kennedy
MARINE...Kennedy
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Prepared by Boulder-Creek.com Weather at: Thu Mar 19 18:30:04 PDT 2026
From the National Weather Service
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