FXUS66 KMTR 190005
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
505 PM PDT Thu Jun 18 2026

...New AVIATION...

.KEY MESSAGES...
Updated at 112 PM PDT Thu Jun 18 2026

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

 - Minor HeatRisk through the end of the week with below normal 
   temperatures expected this weekend

 - Temperatures warm and Moderate HeatRisk concerns return by 
   midweek across the interior

&&

.SHORT TERM...
Issued at 112 PM PDT Thu Jun 18 2026
(This evening through Friday)

Stratus is receding across with the interior while it persists along 
the coast. Patchy clearing is expected along the coastline this 
afternoon before overcast conditions return this evening. A deep 
upper level trough moving into the West Coast is helping the marine 
layer to deepen and will bring a very low, but non-zero, chance of 
thunderstorms to far northern Sonoma and Napa Counties along the 
highest ridgelines. The marine layer is currently between 2000-2500 
ft and is expected to remain around that depth through Friday. Given 
the deep marine layer and widespread cloud cover this morning, I 
continued to lower daytime temperatures for areas below 2000 feet 
today and again tomorrow. For Thursday, high temperatures will be in 
the 60s along the coast and 70s across the interior lower 
elevations. Areas above the marine layer will be warmer, with 
temperatures in the 70s to 80s. High temperatures on Friday will be 
slightly cooler with highs in the 60s along the coast and 70s across 
the interior. Breezy onshore winds (20-30 mph) are possible across 
the higher elevations and favored mountain gaps/passes (Altamont 
Pass, San Bruno Gap, Salinas Valley, etc). 

A non-zero, but very low, chance of thunderstorms exists for far 
northern Sonoma and Napa Counties tonight into tomorrow. The current 
forecast shows a <5% chance of thunderstorms which is a decrease 
from yesterday. In terms of the environment, there is decent mid to 
upper level moisture but little to no instability. The bulk of the 
moisture and instability are to our north (EKA's CWA) and to our 
east (STO's CWA). There is a brief period where thunderstorm 
potential looks marginally more promising this evening across 
northern Sonoma/Napa Counties but even this is still a less than 5% 
chance. If a thunderstorm is able to develop, it is likely to be 
tied to the highest ridgelines along far northern Sonoma and Napa 
Counties. While thunderstorms remain unlikely, the more likely 
scenario is widespread drizzle along the coast. Precipitation will 
be light with totals amounting to less than a tenth of an inch. 
While this is not a lot of rain, it may be enough to wet coastal 
roads and make them slick. Drizzle is most likely overnight Thursday 
night into Friday morning which may impact any early morning 
commuters.

&&

.LONG TERM...
Issued at 112 PM PDT Thu Jun 18 2026
(Friday night through next Wednesday)

Below normal temperatures and troughing persist through the weekend 
before a pattern change takes place Tuesday/Wednesday of next week. 
Interior highs will be in the 70s on Saturday while coastal areas 
stay in the 50s to 60s. Temperatures start to rise Sunday into 
Monday with interior highs returning to the upper 70s to mid 80s 
while cooler weather persists along the coast. Upper level troughing 
will have progressed eastward by Tuesday with a strong upper level 
ridge replacing it. The center of this ridge will be over the desert 
southwest but it will bring a return of warmer temperatures to the 
Bay Area and Central Coast. The current forecast keeps the hottest 
weather across the interior Central Coast, Southern California, and 
the Central Valley where 90s to low 100s are possible. Temperatures 
across the Bay Area are forecast to reach the 80s to low 90s 
starting Tuesday. Confidence is low to moderate in the late week 
temperature forecast given the strength of the ridge and the 
relatively large model ensemble spread of forecast temperatures. Not 
currently anticipating record breaking heat from this ridge but 
would not be surprised if the forecast temperatures did go up 
slightly next week as this event gets closer in time. Probabilistic 
HeatRisk shows around a 15-20% chance of seeing Moderate HeatRisk 
mid next week across the interior Bay Area. This is definitely worth 
keeping an eye on and is a reminder that, despite our currently 
below normal temperatures, it is summer and temperatures are warming 
up. If you are participating in any outdoor activities, make sure to 
drink plenty of water and to take breaks in the shade as needed.

&&

.AVIATION...
(00Z TAFS)
Issued at 446 PM PDT Thu Jun 18 2026

Breezy south and west winds will continue through the early
evening with wind gusts 20-30 kts, highest VCTY KAPC and KSFO. 
Winds will ease some this evening tough still be persistent 
through the night into Friday. Low clouds are beginning to 
increase in coverage the areas surrounding the San Francisco Bay,
as well as the Santa Cruz area. MVFR will remain in place through
the morning hours with slow clearing expected 16-20Z for areas 
closer to the coast. Confidence in marine layer depth and inland 
spread is moderate to high and should be similar to what was 
observed this morning, potentially slightly deeper. 

Vicinity of SFO...Gusty southwest winds expected through this
evening with gusts in the 20-25 kt range until 03Z Fri. Winds 
will then ease and the marine layer will begin to move back 
inland, with MVFR cigs around 1500-1700ft likely reaching the 
terminal by around 06-07Z with moderate confidence on timing and
cig heights. Conditions will improve again after sunrise, with 
cigs forecast to erode by 16-18Z Fri. 

SFO Bridge Approach...Lingering clouds over the bay may
continue to reduce visibility for the next few hours. Otherwise
conditions should be similar to SFO. 

Vicinity of SJC and OAK...VFR conditions should prevail through
the evening at both SJC and OAK with west to southwest winds of 
around 15-20 knots through early evening, weakening after sunset.
Low stratus deck around 1500ft is forecast to move back into OAK 
around the same time as the wind dies down and will persist 
through around 15z, while intermittent cigs possible 11-15Z Fri
VCTY SJC with cigs closer to 2000ft. Confidence in MVFR 
conditions at SJC is lower and have included only a TEMPO group 
for cigs around 2000ft in the 11-15z time frame. 

Monterey Bay Terminals...Marine stratus hovering over the Santa
Cruz region will become more widespread over the Monterey Bay over
the next few hours. Lower confidence on cig timing with time range
near 01-04Z for areas near MRY and SNS. MVFR conditions expected
through Friday morning with cigs near 1500ft. Low to moderate
confidence in clearing time on Friday near 21Z Fri.

&&

.MARINE...
(Today through Tuesday)
Issued at 927 AM PDT Thu Jun 18 2026

Winds will increase this afternoon and early evening and once
again on Friday afternoon and early evening leading to hazardous
conditions for small crafts in the San Pablo Bay, San Francisco
Bay, Suisun Bay and Monterey Bay. Expect moderate chop along with
the increasing afternoon winds each day. Southwesterly swell with
light to moderate seas will continue into the weekend, with
moderate west to southwest winds across the outer waters.

&&

.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 Saturday night for CAZ006-
     505-509-529-530.

PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-SF 
     Bay N of Bay Bridge.

     Small Craft Advisory from 3 PM to 9 PM PDT Friday for Mry Bay-SF 
     Bay N of Bay Bridge.

&&

$$

SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Roser
MARINE...Manning

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Prepared by Boulder-Creek.com Weather at: Thu Jun 18 18:30:02 PDT 2026