FXUS66 KMTR 291850
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1150 AM PDT Sun Mar 29 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1058 AM PDT Sun Mar 29 2026
- Daily record temperatures expected today
- Cooling trend starts Monday
- Chance for light rain Tuesday - Thursday
&&
.SHORT TERM...
Issued at 1058 AM PDT Sun Mar 29 2026
(This afternoon through Monday)
Clear skies dominate the cwa outside of Big Sur as the ridge
continues to hang on. The big question is if we will set record
max temperatures this afternoon. The 12Z sounding found an 850 mb
temperature of 15.6 C, somewhere between the 90th percentile and
daily max(13.5, 19.6). Lower down, the 925 mb temperature was
measured at 20.6 C, well above the 19.6 record for 12Z
observations on this date. That's a strong indication that we will
have a chance to break temperature records as the sun heats up
the surface and breaks the low-level inversion. San Jose looks
particularly susceptible today. The record is 82 degrees from
2018. It's already 71 degrees as of 11 AM. The latest forecast
calls for 85 degrees. GFSLAMP and HRRR and warmer at 86 and 87
degrees, respectively. Other stations to watch include Oakland,
Santa Rosa, San Rafael, Napa, and Richmond. The only fly in the
ointment is high clouds. The PW is actually decently high at
0.6". Most of the higher humidity air is above 500 mb, where the
lapse rates support some instability. This combination supports
high clouds and long lasting contrails that will filter the
afternoon sunshine and take some edge of the max temperature. The
current visible satellite shows the current high clouds are
pretty thin, however and the impact will likely be limited.
Monday will be a transition day as the ridge finally starts to
break down ahead of an approaching trough. The persistent high
level moisture, combined with the divergent area of the jet stream
downstream of the approaching trough will lead to broken to overcast
mid and high level clouds for most of the day. These clouds,
combined with the gradually lowering 1000-500 mb thickness will
drop inland temperatures by roughly 10 degrees compared to
Sunday. There is a very small chance the clouds Monday will
produce any rain, but it's not out of the question for a few drops
to hit the ground Monday night.
&&
.LONG TERM...
Issued at 1058 AM PDT Sun Mar 29 2026
(Tuesday through next Saturday)
Rain chances return to the forecast in earnest Tuesday. It feels
good to type that following what will very likely go down as the
warmest and driest March in the last 100 years. Unfortunately the
uncertainty mentioned on Friday looks to be resolving towards the
drier solution. The ensemble clusters now agree that the core of
the 500 mb low will move through the Pacific Northwest, leaving
the Bay Area with just the tail end of a long cold front. Some
light prefrontal rain is likely on Tuesday with a pre-frontal
moisture push focused on the Central Coast. The cold front will
move through sometime late Wednesday or early Thursday. Frontal
passage will bring the best chance of rain for the Bay Area. Our
current forecast calls for around 1/10th of an inch on average,
with up to 1/4" in the coastal mountains, and next to nothing
across the interior rain shadowed areas (San Jose, interior East
Bay, etc). Some lingering showers are possible through the day
Thursday, but any instability will be limited by very dry air (PW
<0.3") behind the front.
While the rain leaves a little to be desired mid-week, the
temperatures will cool down back to seasonal normals (generally
60s in the afternoon). At least for a short time. By Friday a new
ridge will start to build, pushing us back into the 70s. The
warming trend continues through the weekend and the interior will
likely be right back in the 80s by Saturday.
The uncertainty really balloons by the 7th or 8th of April.
Roughly 40% of the ensemble members support troughing and cooler
temperatures, while the other 60% show continued ridging hanging
on.
&&
.AVIATION...
(18Z TAFS)
Issued at 1010 AM PDT Sun Mar 29 2026
Currently VFR at all terminals with high clouds streaming in and
stratus remaining confined to the Big Sur Coast. Moderate to high
confidence on VFR prevailing through the TAF period. Tonight another
southerly surge may try again and conditions will cool and moisten
with an approaching cold front, but confidence is low that sub-VFR
conditions will develop at the terminals as a result. Diurnal winds
will prevail. Haze will reduce slant range visibilities.
Vicinity of SFO...Currently VFR with light northeasterly flow. High
confidence in VFR through the TAF period. Winds will back through
the TAF period, maintaining diurnal patterns.
SFO Bridge Approach...Similar to SFO.
Monterey Bay Terminals...Currently VFR and calm at MRY and VFR with
drainage flow at SNS. Moderate confidence on VFR prevailing through
the TAF period. A southerly surge may try again tonight, but
confidence is low that it'll impact the terminals. Even if the
terminals aren't directly impacted, low ceilings/visibilities should
be expected within the area, especially along the Big Sur Coast.
Diurnal winds will prevail.
&&
.MARINE...
(Today through Friday)
Issued at 1010 AM PDT Sun Mar 29 2026
A moderate northerly breeze and moderate seas continue through
Monday before winds weaken and shift to a SW direction Tuesday. A
cold front will move through Wednesday, followed by near gale
force NW winds and rough seas Thursday into Friday.
&&
.CLIMATE...
Issued at 952 PM PDT Sat Mar 28 2026
Here are the record high temperatures at the long term sites for
March 29th.
Location March 29th
Santa Rosa 86 in 2018
San Rafael 85 in 2018
Kentfield 84 in 1935
Napa 83 in 2018, 1968
Richmond 79 in 1968
Livermore 85 in 2015
San Francisco 81 in 2018
SFO Airport 81 in 2018
Redwood City 85 in 2018, 1968
Half Moon Bay 77 in 2004
Oakland 79 in 2003
San Jose 82 in 2018
Salinas Airport 86 in 2018
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory from 3 PM this afternoon to 9 AM PDT Monday
for Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...Sarment
MARINE...Flynn
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Prepared by Boulder-Creek.com Weather at: Sun Mar 29 12:30:02 PDT 2026
From the National Weather Service
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