FXUS66 KMTR 231923
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1223 PM PDT Tue Jun 23 2026
...New SHORT TERM, LONG TERM...
.KEY MESSAGES...
Updated at 1219 PM PDT Tue Jun 23 2026
- Hazardous beach conditions along the Pacific Coast through
Wednesday
- Warming peaks today and Wednesday with Minor HeatRisk
- An upper trough settles over the West Coast by late week,
bringing cooler temperatures and breezy to gusty winds
&&
.SHORT TERM...
Issued at 1219 PM PDT Tue Jun 23 2026
(This evening through Wednesday)
The marine layer is sufficiently deep around 1200-1500 ft today with
satellite showing steady erosion for the inland valleys. Subtle weak
ridging remains in place through Wednesday, helping compress the
marine layer into Thursday morning. As low clouds push inland again
tonight, slightly less inland spread and an uptick in coastal fog
can be expected to accompany the shallower marine layer, with
visibility impacts most prevalent for coastal terrain. As such,
clouds may burn off earlier in the day on Wednesday for most areas,
encouraging similar or slightly warmer high temperatures compared to
today, especially for the valleys. Minor HeatRisk will be one of the
main threats for the short term, peaking today and tomorrow as
valleys and inland spots reach the 80s and interior areas reach the
90s. Despite this warming trend, model guidance has actually been
over-performing with highs for the South Bay as it struggles to
resolve the shallower marine layer. Have lowered temps slightly for
each day through Thursday, primarily for the areas where marine
layer influence will linger into the late morning/early afternoon.
The other primary concern remains the long-period southerly swell
impacting the Pacific Coast beaches into Wednesday afternoon. There
is a high risk for sneaker waves and strong rip currents...never
turn your back to the ocean. Additional information can be found in
the Beach Hazard Statement and the Beaches discussion section
below.
&&
.LONG TERM...
Issued at 1219 PM PDT Tue Jun 23 2026
(Wednesday night through next Monday)
A large upper-level low will start meandering down along the
Canadian coastline for the latter half of the week, decreasing
heights over the region with a much deeper marine layer Friday and
into the weekend. As cooler, moist air fills in, marine layer depth
should push closer to 1500-2000ft as early as Friday morning, with
significantly cooler temperatures for interior areas. Highs will
fall 4-8 degrees Friday compared to Thursday for inland spots, with
further cooling into Saturday as heights continue to fall with the
approach of the low. By Saturday morning, the marine layer will be
deep enough to support patchy drizzle, primarily for the coastal
areas.
As the low approaches, a tightening gradient will bring gusty
onshore winds for much of the region as early as Friday, with higher
confidence for Saturday and Sunday. Gusts may exceed 40 mph at
times, especially for wind-prone areas and mountain passes. Winds
weaken Sunday as the low moves up into Montana and weak ridging will
attempt to move back into the area. At this time, some long-range
models suggest a prevailing troughing pattern that may limit warming
for next week, but temperatures should improve a bit compared to the
Friday/Saturday cooldown.
&&
.AVIATION...
(18Z TAFS)
Issued at 1040 AM PDT Tue Jun 23 2026
Marine stratus will continue to erode toward the coast and nearly
all terminals should be VFR within the next few hours, the
exception being KHAF where low cigs will likely persist through
the afternoon. Typical diurnal wind pattern expected this
afternoon, easing through the evening. Similar cloud bases
returning to most areas this evening through Wednesday morning.
Vicinity of SFO...VFR conditions will prevail through the
afternoon with winds increasing out of the NW/W. A few gusts to
near 25 knots will be possible. MVFR conditions forecast to return
by 04z Wed as marine stratus moves back into the area, becoming
IFR shortly thereafter. Conditions should improve by mid/late
morning, with a return to VFR conditions around 18z.
SFO Bridge Approach...Similar to SFO. Increased chance of BKN
cigs to linger in the afternoon hours.
Vicinity of SJC and OAK...Marine stratus will likely persist for
another couple hours at OAK. Otherwise, VFR conditions will
prevail through the afternoon with a typical diurnal increase in
winds to around 15 knots. Winds ease and MVFR clouds roll back in
between 04z and 08z. OAK likely to see IFR conditions for much of
the 06-16z Wed timeframe. Expect improving conditions after 15z
with a return to VFR conditions during the late morning to early
afternoon.
Monterey Bay Terminals...Stratus has already cleared at SNS and
is forecast to clear in the next 2-3 hours at MRY. There is some
potential that NW flow aloft will result in only intermittent
scattering to MRY, so will need to keep an eye on both satellite
and surface observation trends. MVFR cigs returning after 01z
Wed, becoming IFR shortly thereafter. Typical diurnal W/NW winds
5-15 kts.
&&
.MARINE...
(Today through Sunday)
Issued at 1040 AM PDT Tue Jun 23 2026
Gentle to moderate winds persist through midweek with generally
moderate seas. Fresh to strong breezes are forecast to resume
over the coastal waters late in the week, resulting in rough seas
across the coastal waters. Long period southwest swell will
persist through the extended forecast.
&&
.BEACHES...
Updated at 1215 AM PDT Tue Jun 22 2026
Long period southerly swell at around 14 to 16 seconds will
increase to 17 to 19 seconds by the middle of the week 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 Wednesday
afternoon. 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 Wednesday afternoon for CAZ006-
505-509-529-530.
PZ...None.
&&
$$
SHORT TERM...Navarrete
LONG TERM....Navarrete
AVIATION...Navarrete
MARINE...Navarrete
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Prepared by Boulder-Creek.com Weather at: Tue Jun 23 14:30:03 PDT 2026
From the National Weather Service
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