FXUS66 KMTR 270703
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1203 AM PDT Thu Aug 27 2026

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

.KEY MESSAGES...
Updated at 1201 AM PDT Thu Aug 27 2026

 - Slight chance of thunderstorms this morning, with shower
   chances through Friday

 - Slight cooling today, with temperatures close to seasonal averages

 - Cooling trend continues Friday into the next week

&&

.SHORT TERM...
Issued at 1201 AM PDT Thu Aug 27 2026
(Today and tonight)

Stratus clouds are developing at the immediate coast and are 
expected to generally remain confined to the coastal valleys 
overnight before mixing out through Thursday morning. Zooming out 
into the Pacific reveals some interesting activity off the coast as 
some storm cells with frequent lightning have developed around a 
moisture gradient. The latest forecast update includes a slight 
chance for thunderstorms for the morning hours, around the time 
that these cells would impact the coast if they hold together. As 
of the time of writing, they have been dissipating as they move 
towards our coastal waters, but the night shift will continue 
monitoring these cells as they approach and issue any forecast 
updates and products as they become necessary. Beyond the morning 
hours, tropical moisture sourced from the remnants of Tropical 
Storm Iselle will come into the state, and slight chances for 
showers persist through the day. Low, but non-zero, chances for 
thunderstorms will tick up again in the afternoon and evening 
hours, but the limiting factor appears to be insufficient 
atmospheric instability. Will continue to monitor the situation as
it evolves through the day.

The large-scale weather pattern remains dominated by the balance 
between the ridging over the Desert Southwest and the troughing over 
the eastern Pacific. The ridging has generally won out over the last 
few days, but today will mark the very beginnings of a transition to 
a more troughing-dominated pattern. Temperatures will remain near to 
slightly above the seasonal averages, but we will see a slight 
cooldown as highs reach the upper 80s to middle 90s inland, the 
upper 90s to the triple digits in the warmest interior locations, 
the lower 70s to the lower 80s near the Bays, and the lower to 
middle 60s at the Pacific coast. Breezy onshore winds will develop 
in the afternoon and evening hours with gusts of 20 to 30 mph at the 
coasts.

For a discussion of weather-related impacts to the fire weather 
situation, see the FIRE WEATHER section.

&&

.LONG TERM...
Issued at 1201 AM PDT Thu Aug 27 2026
(Friday through Wednesday)

The progression of the trough, and with it the cooling trend and 
associated tropical moisture, continue into Friday with the slight 
chances for showers continuing through the day. Later on Friday into 
the weekend, the tropical moisture dips to the south but the 
deepening trough remains, and cooler temperatures continue into the 
middle of next week. Temperatures reach their coolest on Monday, 
around 5 to 15 degrees below seasonal averages, as high reach the 
70s throughout the inland valleys, the 80s along the warmest 
interior Central Coast regions, and the upper 50s to the 60s at the 
Bays and the Pacific coast. The trough will start to flatten out, 
but remains in place with temperatures slow to rise. The forecast 
shows rain chances returning to the region for the middle of next 
week, but this is critically dependent on how conditions evolve in 
the tropical Eastern Pacific, so confidence remains low.

&&

.AVIATION...
(06Z TAFS)
Issued at 841 PM PDT Wed Aug 26 2026

It's VFR across the forecast area except in the area of the Timber
Fire smoke and haze may reduce slant range and surface visibilities.
24 hour trends continue mainly warmer and drier across the forecast
area and satellite imagery shows stratus and fog recently reaching
the coastline. The ACV-SFO pressure gradient is 4.0 mb and the
SFO-SAC pressure gradient is 2.5 mb. Coastal stratus and fog
/IFR-LIFR/ will redevelop tonight and Thursday morning under a 
compressed marine layer. Coastal stratus and fog mix out to VFR by
late Thursday morning and afternoon.

Vicinity of SFO...VFR. West wind easing to near 10 knots tonight and
Thursday morning. West wind increasing to 20 to 25 knots Thursday
afternoon to mid evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR except tempo stratus and fog /IFR-LIFR/
11z-15z Thursday morning. Mid level clouds may result in a passing
high based shower Thursday afternoon.

&&

.MARINE...
(Tonight through next Tuesday)
Issued at 837 PM PDT Wed Aug 26 2026

Fresh to strong northwest winds will continue tonight and into
the weekend with moderate wind driven seas. Occasional gale force
gusts in the outer and inner waters are expected through the
weekend. A long period southerly swell will build late in the week
becoming 17-18 seconds by Friday and persist through at least
early Sunday.

&&

.BEACHES...
Issued at 1201 AM PDT Thu Aug 27 2026

One more day of near-critical fire weather conditions above 1000 
feet, especially across the Central Coast, as warm and dry 
conditions continue above the marine layer inversion and overnight
humidity recoveries remain poor. One thing to note is that even 
with the slight chance of rain today into Friday, we are not 
expecting wetting rains to develop, while a small but non- zero 
chance for thunderstorms raises the specter for a dry lightning- 
induced fire start in the higher elevations. Across the Timber and
Plaskett Fires, light offshore winds overnight may lead to 
nocturnal drying concerns at the higher elevations. A pattern 
change Friday into the weekend will bring cooler temperatures and 
likely a deeper marine layer, bringing progressively more relief 
to some of the higher elevations. 

DialH

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT Friday for 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.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...Canepa
MARINE...Canepa

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Prepared by Boulder-Creek.com Weather at: Thu Aug 27 00:30:02 PDT 2026