FXUS66 KMTR 210817
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
117 AM PDT Sun Jun 21 2026

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

.KEY MESSAGES...
Updated at 1230 AM PDT Sun Jun 21 2026

 - Hazardous beach conditions with increased risk of sneaker waves
   and strong rip currents continue through the extended forecast

 - Temperatures will increase through the middle of the week

 - Moderate HeatRisk concerns return midweek across the interior

&&

.SHORT TERM...
Issued at 1230 AM PDT Sun Jun 21 2026 
(Today and tonight)

Satellite imagery reveals stratus gradually expanding back across
the area early this morning, although it is less extensive than
the previous couple of nights at this time. Expect stratus to fill
in along the coast and inland valleys by sunrise, then retreat
back to the coast by late morning. The marine layer will compress
further today as upper troughing along the coast weakens. This 
should keep more clouds along the coast this afternoon compared to
the clearing experienced Saturday. Expect warmer temperatures in
most areas this afternoon, especially across the interior which 
will warm as much as 5-10 degrees from Saturday. Highs will 
increase a few degrees along SF Bay shoreline, with little change 
right along the coast. This will place highs in the upper 50s to 
around 70 near the coast, with mid 70s to 80s in the interior, and
the warmest spots reaching 90 degrees. Expect typical onshore 
breezes this afternoon and evening, with gusts 15-30 mph, 
strongest in gaps/passes.

The marine layer will be around 1000-1500 feet deep tonight. This
will allow low clouds to move back into inland valleys. The more 
compressed marine layer may allow patchy fog to develop along the 
coast and in wind-sheltered valleys.

We continue to highlight a long-period southerly swell will bring
a risk for sneaker waves and strong rip currents, with a Beach 
Hazards Statement out through Wednesday. If heading to the coast, 
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! For more information, see the BEACHES section.

&&

.LONG TERM...
Issued at 1230 AM PDT Sun Jun 21 2026 
(Monday through Saturday)

A building upper level ridge will keep the marine layer compressed
and continue a warming trend through the middle of the week. 
Highs will warm a few degrees each day, reaching their peak on 
Wednesday. However, highs Tuesday and Thursday will also be quite 
warm and within a couple degrees of Wednesday's readings. Marine 
influence should limit warming along the coast and bays with highs
in the 60s and 70s, but this will still be several degrees warmer
than today. Across the interior, highs will reach the 80s and 
90s. Hot temperatures, especially inland, will be accompanied by 
pockets of Moderate HeatRisk with increased heat impacts. The 
trend still holds from the previous discussion that coverage of 
Moderate HeatRisk looks too limited for a Heat Advisory. However, 
hot temperatures may produce a risk for heat-related illnesses 
amongst sensitive populations, including children, the elderly, 
pregnant women, people with chronic illnesses, and people who work
or live outdoors without access to adequate cooling or hydration.

Latest ensemble guidance continues the trend of keeping
moisture/instability rotating around the ridge to our east. This 
means thunderstorms next week are highly unlikely, but any 
potential will continue to be monitored. Late this week,
temperatures trend cooler as an upper trough moves into the
Pacific Northwest. It will remain dry in our area, but winds may
become breezy as this system moves by to the north.

&&

.AVIATION...
(06Z TAFS)
Issued at 852 PM PDT Sat Jun 20 2026

VFR conditions prevail due to carryover mixing within the boundary
layer from earlier in the day. A shallow cool front will move 
southeastward along the CA coast, combining with post sunset 
radiative cooling this will bring a return of stratus /MVFR-IFR/ 
tonight and Sunday morning. Thermal ridging will persist aloft 
during the period. Patchy light coastal drizzle is possible 
tonight and Sunday morning. Coastal stratus mixes out to MVFR-VFR 
late Sunday morning and afternoon. Coastal stratus redevelops
Sunday night and Monday morning.

Vicinity of SFO...Stratus /MVFR/ is forecast to return to the 
terminal. Stratus /MVFR/ and tempo light drizzle tonight and 
Sunday morning. Conditions improve to VFR by 18z Sunday. Stratus 
/MVFR/ returns by mid Sunday evening. West wind 11 to 18 knots 
due to the incoming cool front tonight. West wind 15 to 25 knots 
redeveloping by 21z Sunday afternoon, easing to near 10 knots mid 
Sunday evening.

SFO Bridge Approach...Similar to SFO.

Vicinity of SJC and OAK...For SJC Airport VFR for the evening, 
stratus /MVFR/ returns by 10z then mixes out to VFR by 18z Sunday.
Northwest wind 10 knots tonight becoming light southeasterly Sunday
morning. Northwest wind redeveloping Sunday afternoon. For OAK 
Airport stratus /MVFR/ prevails tonight and Sunday morning, mixing
out to VFR by 18z. Also, tempo light drizzle 11z-15z Sunday. West
wind 5 to 15 knots.

Monterey Bay Terminals...Stratus /MVFR/ returns this evening, 
stratus prevails with tempo light drizzle tonight and Sunday 
morning. Conditions improving to VFR late Sunday morning and
afternoon. Stratus /MVFR-IFR/ returns Sunday evening and night. 
Onshore winds 5 to 15 knots.

&&

.MARINE...
(Tonight through next Friday)
Issued at 843 PM PDT Sat Jun 20 2026

Fresh to strong winds in the northern outer waters now through
early Monday morning, leading to hazardous conditions for small
craft. Otherwise, across the inner and outer waters winds will
remain light to moderate. Long period southwest swell continues
through the forecast period.

&&

.BEACHES...
Issued at 308 AM PDT Sat Jun 20 2026

Long period southerly swell at around 15 to 17 seconds will
persist for the remainder of the weekend, and increase to 17 to 
19 seconds by the middle of the upcoming work 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...Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt 
     Reyes 10-60 NM.

&&

$$

SHORT TERM...Tangen
LONG TERM....Tangen
AVIATION...Canepa
MARINE...Malarkey

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Prepared by Boulder-Creek.com Weather at: Sun Jun 21 04:30:03 PDT 2026