FXUS66 KMTR 201613
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
913 AM PDT Sat Jun 20 2026
...New UPDATE, MARINE...
.KEY MESSAGES...
Updated at 1245 AM PDT Sat Jun 20 2026
- Hazardous beach conditions with increased risk of sneaker waves
and strong rip currents continue through the extended forecast
- Minor HeatRisk with below normal temperatures through the
weekend
- Warmer temperatures and Moderate HeatRisk concerns return by
midweek across the interior
&&
.UPDATE...
Issued at 858 AM PDT Sat Jun 20 2026
Rinse and repeat kinda morning around the Bay Area and Central
Coast weather wise to start the day. Satellite, cams, soundings,
and profilers show another robust marine layer blanketing the
region. Automated gages also measured some light accumulating
drizzle. All that being said, there are some differences in the
details. Recent satellite trends already show some thinning of the
stratus deck. The OAK sounding from this morning shows a less
dramatic marine inversion. As such, expect an earlier clearing
time than yesterday. In fact, some coastal area even have a shot
at seeing the sun this afternoon.
No update needed as current forecast captures this trend.
Please heed the advice in the beaches section below if you're
going to the beach. With more afternoon sunshine expected we may
see a few more beachgoers.
MM
&&
.SHORT TERM...
Issued at 1245 AM PDT Sat Jun 20 2026
(Today and tonight)
The pattern overall will remain similar today as a broad upper
level trough sits overhead. Stratus will expand across most areas
this morning within a marine layer around 3000 feet deep. Drizzle
may develop along the coast this morning as well, resulting in
locally slick roadways. The deep marine layer and continued
onshore flow will keep temperatures similar to yesterday, with
highs along the coast ranging from the upper 50s to around 70.
Inland, temperatures will remain below normal with highs reaching
the 70s to lower 80s. Clouds should retreat back to the coast this
afternoon, giving way to sunny skies in most areas. However,
clouds may not fully erode in coastal areas due to onshore flow
and orographic effects. Onshore winds will once again be breezy
this afternoon and evening with gusts 15-30 mph, strongest in
gaps/passes.
The marine layer will begin to compress tonight as the upper
level trough weakens. Marine stratus will still fill in most
valleys tonight, but the extent should be lower overall. Patchy
fog will also be possible along the coast and in wind-sheltered
valleys.
&&
.LONG TERM...
Issued at 1245 AM PDT Sat Jun 20 2026
(Sunday through Friday)
The upper level trough will continue its weakening trend on Sunday
and the marine layer will compress further. Decreasing marine
influence and warming temperatures aloft will begin a warming
trend, especially inland, where many locations will reach the 80s,
with a few readings approaching 90 degrees in the warmest spots.
The warming trend will continue Monday and Tuesday as a broad
ridge builds across the western U.S. Highs will reach the 80s and
90s through the week across the interior. Hot temperatures will be
accompanied by the potential for Moderate HeatRisk and increased
heat impacts, although overnight cooling limits concerns somewhat.
Closer to the coast, confidence in the temperature forecast is
lower, but at least some warming is expected. More significant
warming along the coast/SF Bay shoreline could develop if a weaker
onshore or offshore wind pattern occurs, but confidence in this
scenario is low. This potential will continue to be monitored as
we head into next week.
As mentioned in previous discussions, ensemble guidance continues
to indicate moisture rotating north around the upper ridge
centered over the Desert Southwest. By Wednesday and Thursday,
there is a low (around 10%) chance that the moisture and
accompanying instability makes it far enough west to bring a
threat for thunderstorms to the Bay Area and Central Coast.
Overall, the chance of this scenario occuring is low, but it
could have a large impact. While the current forecast package does
not include thunderstorms, this potential will continue to be
closely monitored over the coming days.
&&
.AVIATION...
(12Z TAFS)
Issued at 442 AM PDT Sat Jun 20 2026
Low clouds have settled into coastal areas and adjacent valleys
this morning. Some areas may see patchy drizzle with very light
accumulations. Stratus will recede back off land around 17 to 19Z
Saturday with VFR conditions prevailing through the early evening.
Low clouds returning to most coastal TAF sites near 1500-2000ft
after 04Z Sun, after 06Z for areas further inland.
Vicinity of SFO...Weaker SW winds expected through the morning.
Cigs scattering out with winds increasing near 15 kts after 19Z
Saturday. Cigs returning similar timing to last evening ~ 07Z Sun,
though lower near 1500-1800ft. Confidence in timing moderate to
high, confidence in cig heights moderate.
SFO Bridge Approach...SW wind pattern is similar to SFO. MVFR
cigs clearing at a similar time to SFO this morning, becoming VFR
by 19Z. Cigs 1500-1800ft returning slightly earlier than SFO
(03-04Z Sunday).
Vicinity of SJC and OAK...MVFR ceilings scattering near 17-19Z,
confidence higher for earlier clearing at SJC. Typical diurnal
winds out of the W/NW this afternoon. Cigs near 1600-1900ft
returning earlier at OAK (05-07Z Sun) than SJC (10-12Z Sun), lower
confidence in exact timing of cig impacts at SJC.
Monterey Bay Terminals...Cigs near 2500-3000ft this morning will
scatter out around 18-20Z with moderate confidence on timing. VFR
conditions prevail through the afternoon with cigs returning near
04-06Z Sun near 1500-1800ft. Typical diurnal winds out of the W/NW
expected Saturday across the bay.
&&
.MARINE...
(Today through Thursday)
Issued at 858 AM PDT Sat Jun 20 2026
Light winds today will increase across the northern outer waters
later tonight and persist through early Monday morning, leading to
hazardous conditions for small craft. Elsewhere across the inner
and outer waters winds will remain light to moderate. Long period
southwest swell is likely to continue 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 from 9 PM this evening to 3 AM PDT Monday
for Pt Arena to Pt Reyes 10-60 NM.
&&
$$
SHORT TERM...Tangen
LONG TERM....Tangen
AVIATION...APR
MARINE...DM
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Prepared by Boulder-Creek.com Weather at: Sat Jun 20 10:30:02 PDT 2026
From the National Weather Service
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