FXUS66 KMTR 042043
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
143 PM PDT Sat Apr 4 2026

...New SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 142 PM PDT Sat Apr 4 2026

 - Warmer temperatures continue today and tomorrow before a 
   cooling trend begins next week

 - Beneficial rain chances increase mid to late next week

&&

.SHORT TERM...
Issued at 142 PM PDT Sat Apr 4 2026
(This evening through Sunday)

Another warm weekend remains on track. Interior highs today are 
largely in the low 80s while coastal areas remain in the 70s. This 
should keep most sites below their daily high temperature records 
but some coastal sites may come close to (or break) their daily 
records. Another warm day is expected on Sunday with temperatures 
rising by a few degrees compared to today. This does not change the 
overall forecast too much between Saturday and Sunday - inland highs 
remain in the low to mid 80s while coastal highs stay in the 70s. 
Winds remain light and offshore tonight through tomorrow morning 
before switching onshore again during the afternoon/evening. In 
terms of the larger synoptic pattern, a pattern change remains on 
track to begin next week but we see the first indications of this 
transition Sunday. This weekend, upper level ridging and high 
pressure have been able to build over California, resulting in 
temperatures warming up and our marine layer being compressed/mixed 
out. Sunday afternoon/evening, the upper level ridge begins to 
progress eastward as weak upper level troughing builds in from the 
Pacific. This will allow the marine layer to redevelop Sunday night 
and bring in a return of stratus and an increased potential for 
coastal drizzle. 

&&

.LONG TERM...
Issued at 142 PM PDT Sat Apr 4 2026
(Sunday night through next Friday)

A pattern change is expected next week with cooler temperatures and 
some light, beneficial, rain mid to late week. As mentioned in the 
short term, a weak, shortwave trough arrives Sunday into Monday 
before transitioning to more zonal flow (horizontal/stable) Monday 
into midweek. This will kick off a cooling trend with inland 
temperatures dropping into the 70s and coastal temperatures into the 
50s to 60s. Inland areas will still be running a few degrees above 
normal but coastal temperatures will be fairly seasonal and right 
around average for this time of year. Out in the Pacific, a cut-off 
low is expected to break off from a deep upper level trough further 
north (closer to Alaska). This cut-off low looks to linger over the 
Pacific until Wednesday and is part of the reason we see a more 
zonal pattern early next week. By Wednesday, the cut-off low looks 
to reabsorb into the synoptic pattern and reaches the West Coast as 
part of a deep upper level trough. It will bring some moisture with 
it (PWAT values around 0.8" to 0.9") but the bulk of the moisture 
will be located farther south. Light rain is expected across the Bay 
Area and Central Coast Wednesday and Thursday with some potential 
for scattered showers Friday. It is low confidence but there is a 
nonzero chance for thunderstorms to develop with this system. In 
terms of temperature, temperatures drop into the 60s across the 
board Thursday and Friday with the warmest locations reaching the 
low 70s.

The real question about next weeks forecast comes from small 
variances in both the strength and location of the trough as it 
moves onshore. Cluster guidance presents two predominant forecasts: 
the low will be reabsorbed into the larger pattern but still
maintain some elements of a cut-off low as it lingers offshore mid
to late week, or, it will fully merge with the upper level trough
and move onshore fairly progressively. Cluster guidance is split
between these two scenarios with each presenting slightly
different outcomes for this week's forecast. If the cut-off low
does fully merge with the trough and moves inwards quickly, we
could see offshore winds develop in the wake of the system
depending on the orientation of the trough. If it maintains
elements of a cut-off low after merging, the potential for
thunderstorms increases slightly across the Central Coast. If the
cut-off low remains stationary offshore (i.e. doesn't progress
inland quickly) then we could see a longer duration of moisture
transport inland resulting in additional light rainfall (largely
over the Central Coast). Whatever way you slice it, the overall
picture of next week remains the same: cooler, more seasonal
temperatures and light, beneficial rain mid to late week. Make
sure to stay up to date on the forecast as next week approaches
and models come into a better consensus on the finer details of
this system.

&&

.AVIATION...
(18Z TAFS)
Issued at 1036 AM PDT Sat Apr 4 2026

Outside of some high clouds streaming in from the southwest, VFR 
is expected to prevail at all terminals through the current TAF 
cycle. Winds will generally be under 15 knots (except at SNS) with
offshore flow becoming onshore later this afternoon. Offshore 
breezes, still under 15 knots, return between 0400-0600Z Sunday. 

Vicinity of SFO...VFR with 5-10 knots easterly winds becoming 
onshore/northwesterly between 2200Z-0000Z. During this time, 
speeds increase to just over 10 knots. Speeds diminish through the
0300- 0400Z this evening with winds becoming variable and 
eventually easterly by daybreak Sunday.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR with passing high clouds. Slightly 
stronger breezes are anticipated at KSNS due to channeling 
through the Salinas Valley. The seabreeze will switch winds to 
onshore later this afternoon around 2000-2100Z. Offshore flow is 
forecast to return this evening with no noteworthy aviation 
concerns anticipated over the next 24 hours. 

&&

.MARINE...
(Today through Thursday)
Issued at 1036 AM PDT Sat Apr 4 2026

Light to moderate northerly winds continue into next week with
coastal jet bringing locally fresh to strong gusts along the Big
Sur Coast midweek. A low pressure system over the Pacific will
approach the region by the middle of next week bringing a chance
of rain, fresh to strong gusts across the northern waters, and
moderate to rough seas. 

High pressure off the Pacific Northwest coast and low pressure 
along the California coast will maintain northerly flow this 
weekend. Light to moderate northerly breezes will persist into 
next week. A low pressure system over the Pacific will approach 
the coastal waters and bays by the middle of next week bringing a 
chance of rain, strong breezes, and moderate seas.

&&

.CLIMATE...
Issued at 110 PM PDT Fri Apr 3 2026

The following are the record high temperatures at the long term 
stations for April 4th and April 5th.

Location          April 4th                April 5th 

Santa Rosa        88 in 1961               90 in 1939
Kentfield         85 in 1957               88 in 1924
San Rafael        86 in 1960               87 in 1957
Napa              86 in 1985, 1960         86 in 1989, 1957
Richmond          89 in 2011               83 in 1989
Livermore         87 in 1959               84 in 1989, 1916
San Francisco     84 in 1985               88 in 1989
SFO Airport       82 in 1985               84 in 1989
Redwood City      86 in 1960               87 in 1989
Half Moon Bay     77 in 2011               74 in 2016
Oakland Museum    85 in 1985               85 in 1989  
San Jose          87 in 1960               89 in 1989
Salinas Airport   86 in 1989, 1960, 1952   95 in 1989

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Bain
MARINE...Kennedy

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Prepared by Boulder-Creek.com Weather at: Sat Apr 4 14:30:03 PDT 2026