FXUS66 KMTR 301618
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
918 AM PDT Sun Aug 30 2026
...New UPDATE, MARINE...
.KEY MESSAGES...
Updated at 1240 PM PDT Sat Aug 29 2026
- Another beautiful day Sunday
- Cooler weather this week
&&
.UPDATE...
Issued at 918 AM PDT Sun Aug 30 2026
Stratus finally filled in across the region early this morning,
especially along the coastline, Monterey Bay/Salinas Valley region,
and around the San Francisco and San Pablo bays. These low clouds
are forecast to retreat to the coast and potentially remain in place
around the Monterey Bay throughout the day. That said, inland areas
away from the coast are expected to see mostly sunny skies this
afternoon. No updates are anticipated this morning as the forecast
remains on track.
RGass
&&
.SHORT TERM...
Issued at 1053 PM PDT Sat Aug 29 2026
(Tonight through Monday)
Saturday was a beautiful sunny day across the Bay Area and Central
Coast and we'll get more of the same on Sunday. The marine layer
stratus fully evaporated by noon as a much direr air mass moved in
from the north. The 00Z weather balloon measured the precipitable
water at 0.58", which is around the 10th percentile for this time of
year. With unimpeded radiative cooling, marine layer stratus is
starting to reform, with Half Moon Bay recording the first clouds
overhead this evening. Coastal areas south of the Golden Gate
will likely see the stratus come back before the sun rises Sunday
morning. Inland valleys are more of a toss-up. The marine layer is
currently 1,600' deep and will gradually expand over the next 24
hours. Any clouds that form will likely clear by midday with a
mild, breezy, and clear afternoon.
Marine layer stratus should be much better organized by Monday
morning. The depth will likely be around 2,000' by then, with less
chance of clearing along the coast. As a short wave trough moves
through, temperatures will also be around 5 degrees cooler than the
weekend with a stronger onshore breeze in the afternoon.
&&
.LONG TERM...
Issued at 1053 PM PDT Sat Aug 29 2026
(Monday night through next Saturday)
As the troughing pattern continues, the 850 mb temperature will
bottom out around 6-10 C on Tuesday. That's about as low as it gets
this time of year and more like a normal November day. High
temperatures will be in the 60s and 70s with the typical marine
layer stratus in the morning. The troughing pattern will deepen and
a cut-off low will bring some early rain to the Pacific Northwest
later this week. There is a chance for some light rain to make it as
far south as the North Bay starting Tuesday. The ECMWF ensemble mean
shows a few hundredths at Santa Rosa from Tuesday through Friday,
with a 10% chance of reaching 1/2". The probability drops quickly
further south outside of some marine layer drizzle along the
coast. This cut-off low now looks like it will linger near
Northern California into the weekend. If so, this low pressure
breaks up the normal subtropical high and opens the door for
tropical cyclones and the associated moisture to recurve to the
north rather than being held in the tropical latitudes. While it's
too early to say if that will happen, the persistent troughing
pattern looks like it may keep the door open into next week.
&&
.AVIATION...
(12Z TAFS)
Issued at 432 AM PDT Sun Aug 30 2026
Scattered IFR-MVFR stratus is developing across the coastal and
Bayshore SF Bay Area and parts of Monterey Bay. The scattered and
radiational cooling-driven nature of the stratus development is
making it difficult to predict where stratus will develop through
the rest of the night, but light winds across the interior should
promote further stratus development through sunrise. Stratus should
dissipate rather quickly after sunrise with lingering clouds
possible at the immediate coast, while a moderate onshore breeze
develops in the afternoon and evening. Tonight, expect more robust
stratus development, especially across the interior, heading into
Monday morning as the marine layer deepens.
Vicinity of SFO... Moderate confidence for momentary stratus
development over the terminal through the morning hours, although
breezy surface winds may provide enough disruption to stratus
formation processes to keep the terminal VFR through the nighttime
hours. Moderate west winds with strong gusts will develop in the
afternoon and evening hours, gradually diminishing with MVFR stratus
expected to develop overnight and persist through Monday morning
past the end of the TAF period.
SFO Bridge Approach... Lower confidence for stratus development
along the approach path through the morning. Otherwise similar to
SFO.
Monterey Bay Terminals... Patches of MVFR stratus are close to or
over the terminals and are expected to persist through the next few
hours before retreating to the immediate coast after sunrise. A
gentle to moderate onshore breeze will develop in the afternoon and
evening hours. Stratus should return to the terminals early tonight
through Monday morning.
&&
.MARINE...
(Today through Friday)
Issued at 918 AM PDT Sun Aug 30 2026
Northwest breezes remain fresh with strong to near gale force
gusts today and gradually diminish to gentle breezes by Monday.
Wind driven rough seas subside to moderate by Monday into the rest
of the week. The long period southerly swell also decreases today
into early Monday morning.
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt
Reyes 0-10 nm.
Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt
to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.
Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt
Reyes 10-60 NM.
&&
$$
SHORT TERM...Flynn
LONG TERM....Flynn
AVIATION...DialH
MARINE...Navarrete
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Prepared by Boulder-Creek.com Weather at: Sun Aug 30 10:30:04 PDT 2026
From the National Weather Service
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