FXUS66 KMTR 180458
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
958 PM PDT Wed Jun 17 2026
...New AVIATION, MARINE...
.KEY MESSAGES...
Updated at 156 PM PDT Wed Jun 17 2026
- Minor coastal flooding due to higher than normal high tides
anticipated across low-lying coastal areas.
- Hazardous beach conditions as well with increased risk of
sneaker waves and strong rip currents.
- Minor HeatRisk through the end of the week with temperatures
cooling to below normal.
&&
.SHORT TERM...
Issued at 156 PM PDT Wed Jun 17 2026
(This evening through Thursday night)
The marine layer, ~1500ft, continues to retreat back towards the
coast, having lingered a bit longer than expected for the San
Francisco Bay and into the northern interior valley, bringing
slightly cooler high temps for today. Expect the marine layer to
push back onshore tonight. Have included drizzle along the coast
as the marine layer slightly deepens as the ridge breaks down as
troughing pushes east towards the coast. Patchy fog for interior
valleys possible as well. The slight cooling trend will continue
into Thursday, especially for interior locations, as a result of
the troughing and slightly stronger onshore flow, with afternoon
highs in the 60s along the coast to mid 70s to 80s for interior
locales. The marine layer builds to ~2000kt and expands further
inland for tomorrow night, with more fog and drizzle expected.
Tidal flooding continues across low-lying coastal and Bayshore
areas through Thursday morning as high astronomical tides combine
with surge effects from wind, swell, and thermal expansion to
bring us the highest tides of the summer season. High tide is
expected to be 1.2 ft above normal (7.1 ft MLLW) at 1:51 AM on
Thursday. In addition, the long-period southerly swell continues,
which increases the risk for sneaker waves and strong rip
currents, with a Beach Hazards Statement out through late Friday
night. See the BEACHES section for more information, but the main
takeaway is to never turn your back to the ocean!
&&
.LONG TERM...
Issued at 156 PM PDT Wed Jun 17 2026
(Friday through Wednesday)
The trough will begin to move onshore on Friday and pass over the
region through the weekend, with the cooling trend continuing.
Shower and thunderstorm potential associated with the trough will
stay primarily over the higher terrain to the north and east of
the area as a deep marine layer greatly inhibits any thunderstorm
potential. However, there will be enough elevated instability for
cumulus development and around a 5% chance of thunderstorms
across far northern Napa and Sonoma counties Thursday night and
Friday with lower chances to the south.
The marine layer will likely deepen as the trough passes through,
with the cooling trend continuing through Saturday. Afternoon
highs temps will only reach the 70s to low 80s for interior
location and upper 50s to mid 60s along the coast. The onshore
flow will continue with breezy afternoon winds. Coastal areas will
could continue to see drizzle.
By Sunday, the trough is expected to weaken as model guidance is
suggesting a ridge building across the western US into next week.
This will bring a warming trend, beginning Sunday into next week,
with a return of some 90s and moderate HeatRisk concerns by
midweek for some interior areas.
&&
.AVIATION...
(06Z TAFS)
Issued at 958 PM PDT Wed Jun 17 2026
MVFR-IFR stratus is expanding into the valleys and will impact most
terminals through the night as the breezy and gusty southwest
pattern winds continue to diminish, with low to moderate confidence
in stratus impacts at LVK and SJC, where the marine layer is thick
enough to bring stratus into both terminals but the lower level
southwest flow may inhibit stratus flow into those areas. The night
shift will monitor conditions through the night. Stratus should
retreat to the coastal areas through Thursday morning and the breezy
and gusty southwest pattern winds should resume in the afternoon.
Vicinity of SFO... VFR with breezy and gusty southwest winds at the
terminal through the next few hours. Due to the downslope flow, have
pushed back the MVFR-IFR stratus impacts to around 10Z. Stratus will
dissipate through Thursday morning with breezy southwest winds
returning to the terminal in the afternoon. Stratus will return to
the terminal area late Thursday night.
SFO Bridge Approach... Lower confidence of stratus impacts tonight
with the large scale southwest flow, as high resolution models tend
to keep the stratus deck away from the approach path. Otherwise
similar to SFO.
Vicinity of OAK and SJC... IFR stratus through the night at OAK,
with breezy west winds diminishing through the next couple of hours.
At SJC, the stratus forecast remains low confidence. High resolution
model output keeps the terminal area clear, but places scattered
MVFR stratus in the vicinity and particularly to the north of the
terminal. If stratus does impact the terminal, the most likely
timing is from 11-15Z. Stratus clears out through Thursday morning
as breezy and gusty winds return to the terminals, with west winds
developing at OAK, and southwest winds developing at SJC. Stratus
returns to OAK late Thursday night.
Monterey Bay Terminals... MVFR stratus has flowed over SNS and will
remain through the night. At MRY, large scale southwest flow has
sheltered the terminal from the larger stratus deck, defying much of
the high resolution model output, but a patch of stratus developing
to the immediate southeast of the terminal suggests that the
ceilings are close by. Stratus will retreat to the immediate coast
Thursday morning and will return to the terminals Thursday evening.
Breezy winds will diminish through the night before resuming on
Thursday afternoon with strong gusts and a turn from a southwest
wind at MRY and a northwest wind at SNS.
&&
.MARINE...
(Tonight through next Tuesday)
Issued at 958 PM PDT Wed Jun 17 2026
West to southwest winds driven by a weak low pressure system in
the northern outer waters will remain gentle to moderate
overnight. Winds increase again for the next couple afternoons and
evenings with strong breezes anticipated, leading to hazardous
conditions for small craft. Light to moderate seas with
southwesterly swell will continue into the weekend. Moderate west
to southwest winds and moderate seas will prevail over the open
ocean into the weekend.
&&
.BEACHES...
Issued at 156 PM PDT Wed Jun 17 2026
Long period southerly swell at around 15 to 17 seconds will persist
through early Saturday as energetic storms in the Southern
Hemisphere continue to affect the California coast, especially for
south and southwest facing beaches. Hazardous beach conditions
are advertised, specifically for moderate to steeply sloped
beaches along the Pacific Coast of the North Bay, San Mateo, Santa
Cruz counties. A Beach Hazards Statement for Pacific Coast
beaches continues through late Friday night. Be sure to check
beach conditions before you head out. Sneaker waves will run up
the beach much farther than other waves, potentially catching
beachgoers by surprise and resulting in people being swept into
the water. Rip currents are strong enough to pull the strongest
swimmers away from shore. Swim near a lifeguard if possible. Stay
back from the beach, and away from jetties, piers, beachside
rocks, and other infrastructure near the water. Never turn your
back to the ocean!
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement through late Friday night for CAZ006-505-
509-529-530.
Coastal Flood Advisory until 5 AM PDT Thursday for CAZ006-506-
508.
PZ...Small Craft Advisory from 3 PM to 9 PM PDT Thursday for Mry Bay-
SF Bay N of Bay Bridge.
&&
$$
SHORT TERM...Slagle
LONG TERM....Slagle
AVIATION...DialH
MARINE...DialH
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Prepared by Boulder-Creek.com Weather at: Wed Jun 17 22:30:03 PDT 2026
From the National Weather Service
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