419 
FXUS66 KMTR 170421
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
921 PM PDT Thu Oct 16 2025

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 144 PM PDT Thu Oct 16 2025

 - Warming and drying trend through Saturday

 - Offshore winds in the higher elevations tonight and again Friday 
   night into Saturday

 - Long period northwesterly swell will bring an increased risk of
   sneaker waves and rip currents to Pacific Coast beaches Friday
   night and into Saturday

&&

.UPDATE...
Issued at 745 PM PDT Thu Oct 16 2025

Warmer across the region thanks to abundant sunshine and a 
warming airmass today. Highs rose 5 to 10 degrees from Wednesday 
to Thursday with max temps reaching the 60s and 70s. Despite the 
overall warm up the hills/mts across the Central Coast were still 
chilly and stayed in the 50s. 

Normally mentioning offshore flow in October would be a fire
weather concern, but recent rains have helped those concerns. 
Synoptically speaking, offshore flow began to develop earlier 
today with SFO-WMC now approaching -4.5mb. Obs over the higher 
terrain are already showing NE flow with occasional gusts over 20 
mph. The offshore gradient is only expected to peak in the -5 to 
-6mb range tonight or weak/moderate category. While breezy in the 
hills and lowering RH not expecting any major impacts. If 
anything, it will help to disrupt the marine layer. Most notable 
offshore flow will be over the N Bay Mts and E Bay Hills.

No update needed.

&&

.SHORT TERM...
Issued at 144 PM PDT Thu Oct 16 2025
(This evening through Friday)

Building surface high pressure across the eastern Pacific will 
result in a warming trend over the next few days as it builds into 
the Great Basin on Friday. Also, a coastal trough will develop over 
the California coast. This will result in north-northeasterly winds 
across the higher terrain, especially across the North Bay overnight 
tonight and into early Friday morning. Wind gusts will generally 
remain below 35 mph in the highest peaks of the North Bay. However, 
fire weather concerns will be limited by the offshore winds not 
being overly strong and recent rainfall. 

There is about a 15-30% chance for fog over the Bay Shoreline early 
Friday morning, yet confidence is not high enough to include in the 
official forecast. Temperatures Friday morning will bottom out in 
the 40s across the North Bay and southern interior Central Coast 
with low 50s elsewhere. 

Any low clouds or fog that do develop will likely dissipate by 
around 10 AM Friday. The offshore flow aloft will result in warming 
temperatures by Friday afternoon when non-coastal areas warm into 
the 70s with low-to-mid 60s at the coast. These temperatures will be 
up to 5 degrees F above seasonal averages under mostly sunny skies. 

&&

.LONG TERM...
Issued at 144 PM PDT Thu Oct 16 2025
(Friday night through next Wednesday)

Friday night and into Saturday morning, offshore winds will persist 
in higher elevations across the North Bay, weaker elsewhere and 
weaker than what we are expecting tonight with temperatures mostly 
in the 50s to upper 40s in the North Bay and southern interior 
Central Coast. 

On Sunday, a cut-off mid/upper level low will develop off of 
southern California and will result in less of a cool down than 
previously expected. This would act to block the approaching upper 
level trough from pushing a cold front across the Bay Area and 
Central Coast. However, temperatures are forecast to cool by a few 
degrees on Sunday. Still expecting offshore winds to develop in the 
higher terrain as the trough moves into the Intermountain West 
Monday and Tuesday. Mostly zonal flow aloft is expected through the 
remainder of next week across the Bay Area and Central Coast. Thus, 
temperatures are forecast to be near normal for this time of year. 

Longer range guidance suggests a wetter pattern developing by next 
weekend (October 25th and 26th) along with cooler temperatures. This 
is reflected in both the 6-10 and 8-14 Day Outlooks issued by the 
Climate Prediction Center. Stay tuned...

&&

.AVIATION...
(06Z TAFS)
Issued at 921 PM PDT Thu Oct 16 2025

VFR is forecast through the evening except for patchy low clouds 
/MVFR-IFR/ developing along the immediate coastline. The evening 
00z Oakland upper air sounding shows a precipitable water of 0.54"
(25th percentile for the time of year) with a good radiative 
cooling window open i.e. drier layer above the boundary layer for 
nocturnal longwave radiative cooling to space. A loss of heat to 
space will cool temperatures near surface dewpoint temps (measure 
of water vapor) tonight and Friday morning with a few areas of fog
including dense fog probable (20-50%, greater than 50% over the 
SF Bay early Friday morning). ECMWF and GFS show cirrus clouds 
arriving from the north tonight and Friday, which may slow 
radiative cooling a little overnight. Diurnal surface heating and 
mixing results in VFR redeveloping Friday.

Vicinity of SFO...VFR continues through the evening. Radiative 
cooling will result in low clouds and mist/fog /IFR/ 11z-15z 
Friday with IFR prevailing until 18z Friday. VFR thereafter for 
Friday. West-northwest wind 10 to 15 knots, decreasing and 
becoming light and variable to light easterly Friday morning to 
mid afternoon. West wind near 10 knots redevelops by late Friday 
afternoon or early evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR however SCT-BKN low clouds /MVFR-IFR/
will form nearby the terminals during the evening, with increasing
probability of LIFR-IFR in fog and low clouds late tonight and 
early Friday morning. Light east to southeasterly winds tonight 
increasing to 5 to 10 knots perhaps up to 15 knots in the Salinas 
Valley late tonight and Friday morning; cool air drainage winds 
will help to mix out the fog /LIFR-IFR/ earlier than usual Friday 
morning. By late afternoon winds shift to onshore 5 to 10 knots.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 918 PM PDT Thu Oct 16 2025

Moderate northwesterly breezes will continue through the end of
this week. A few gusts will be strong, favoring the outer waters
and south of Pigeon Point for the inner waters. A longer period
northwesterly swell arrives this weekend 7 to 10 feet at 15
seconds.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement from Friday evening through Saturday 
     evening for CAZ006-505-509-529-530.

PZ...Small Craft Advisory until 3 PM PDT Friday for Pt Arena to Pt 
     Reyes 10-60 NM.

&&

$$

SHORT TERM...RGass
LONG TERM....RGass
AVIATION...Canepa
MARINE...Canepa

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