Technical NOAA Weather Discussion

FXUS66 KMTR 100301
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
801 PM PDT Tue Jun 9 2026

...New UPDATE, FIRE WEATHER, BEACHES...

.KEY MESSAGES...
Updated at 750 PM PDT Tue Jun 9 2026

 - Warmer and dry weather expected Wednesday - Saturday

 - Moderate risk of heat-related illnesses for interior locations on 
   Wednesday and Thursday

 - Increased risk of sneaker waves and strong rip currents along
   south and southwest facing beaches through Thursday morning

 - Critical fire weather concerns for the interior North Bay and
   the East Bay Mountains late Wednesday into Thursday morning

 - Elevated fire weather conditions for the Santa Clara Hills late 
   Wednesday into Thursday morning.

&&

.UPDATE...
Issued at 750 PM PDT Tue Jun 9 2026

A Beach Hazards Statement has been issued for the Pacific Coast of
the North Bay, San Mateo, and Santa Cruz counties as long period 
south swell has been creating an increased risk of sneaker waves 
and strong rip currents through Thursday morning. More details
will be available in the BEACHES section. Otherwise, skies remain
clear and the forecast remains on track.

DialH

&&

.SHORT TERM...
Issued at 335 PM PDT Tue Jun 9 2026
(This evening through Wednesday)

The pattern change continues as a front worked its way through the 
region earlier this morning. Behind it, drier air filled in clearing 
the clouds and leading sunny skies and a warm afternoon. High 
temperatures appear to be on track, with interior valley locations 
making it into the upper 70s to mid 80s while coastal and some Bay 
shoreline communities made it into the upper 50s to the mid 70s. 
Dry air will continue to nestle in, which should keep skies clear 
tonight. Low temperatures will generally be in the 50s for most 
sites, though temps in the 60s will be possible for areas at or 
above the thermal belt. 

Tomorrow, Wednesday, the warming trend really kicks off. High 
pressure builds to the west of us, while upper level troughing moves 
east. Drier air and northerly winds will help usher in warmer air to 
the region. Many interior locations, both for mountains and interior 
valleys for the Bay Area and the Central Coast have a Moderate 
threat for HeatRisk. What does that mean? This type of heat affects 
those who are sensitive to heat, especially  those without cooling 
and hydration, and some health and industries. In terms of high 
temperatures, they will vary from the mid 70s to the mid 80s around 
the Bay Shoreline, the upper 80s to mid 90s for interior valleys and 
mountains, and the low 60s to mid 70s for the coastal communities. 

Wednesday night into Thursday morning, there will be some reprieve 
from the heat, as valley locations and areas beneath the thermal 
belt drop into upper 50s to low 60s. For those in the thermal 
belt, overnight lows will be warmer and in span the low 60s to 
upper 70s. This is also when the offshore flow / north to 
northeast winds pick up, particularly across the interior North 
Bay Mountains and the East Bay Hills. Peak wind gusts up to 45 mph
can be expected and ridge top wind gusts may exceed 60 mph. Winds
will be strongest overnight and then begin to ease around 
sunrise. These hot, dry, and windy conditions combined with mixed 
vegetation, such as drying or dead grass, will lead to near 
critical to critical fire weather conditions. A Red Flag Warning 
has been issued for these areas starting late Wednesday night and 
continuing into Thursday morning. 

&&

.LONG TERM...
Issued at 335 PM PDT Tue Jun 9 2026
(Wednesday night through next Monday)

The pattern holds on Thursday, which will lead to our warmest day of 
the week. Many locations will experience Moderate HeatRisk across 
the Bay Area and the interior Central Coast. High temperatures will 
vary from the low 80s to the mid 90s around the Bay Shoreline, the 
upper 80s to the low 100s for interior valleys and mountains, and 
the low 60s to low 80s for the coastal communities. With that being 
said, a Heat Advisory will go into effect on Thursday from 12pm-
11pm: the Bay Shoreline, North Bay Interior Mountains and Valleys, 
and the Santa Clara Valley and Eastern Hills.

Starting on Friday, the NBM begins a gradual cool down across the 
region. This will have to be something we watch closely as there 
is no defining synoptic feature that changes the pattern. Meaning 
we could see another day of warmer temperatures. Some models try 
to bring a marine influence back into the region, but that may 
struggle depending on the strength of the high. Opted to trend a 
few degrees warmer on Friday, given the current model diagnosis 
but should we see marine influence, the NBM may be on to 
something. Saturday, an upper level shortwave tries to form over 
the northern part of the state. This may bring another burst of 
northerlies depending on the placement or usher in onshore flow. 
Opted to generally keep the gradual decrease / moderation of 
temperatures for the weekend and into early next week. 

&&

.AVIATION...
(00Z TAFS)
Issued at 620 PM PDT Tue Jun 9 2026

Widespread VFR through the TAF period. Moderate to breezy winds 
reduce into the evening and become light overnight across the 
region. A building dry airmass will prevent chances for cloud cover 
and fog formation. Expect light winds to last into the late morning 
and early afternoon before becoming more moderate westerly winds 
arrive. 

Vicinity of SFO...VFR through the TAF period. Breezy west winds 
reduce into the light and become light by the mid morning. Moderate 
winds return Wednesday afternoon but ease again that night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR through the TAF period. Expect light 
winds into the night and through much of the morning. SNS sees winds 
increase into the mid morning while winds stay light at MRY. Breezy 
northwest winds return in the mid afternoon.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 335 PM PDT Tue Jun 9 2026

Gusty northwest winds have spread across the waters resulting in
hazardous conditions for small craft. Gale force gusts will spread
across the northern waters overnight night into early Thursday.
Wind and seas begin to ease by Thursday evening and are expected
to stay light through the remainder of the forecast period.

&&

.FIRE WEATHER...
Issued at 750 PM PDT Tue Jun 9 2026

Hot temperatures, gusty north winds, and low humidities across the 
North Bay interior mountains into the Diablo Range will raise the 
fire weather threats late on Wednesday into Thursday, with a 
particular emphasis on the interior mountains of Napa County. Red
Flag Warnings have been issued for the interior mountains of the
North and East Bay from 11 PM Wednesday night through 9 AM 
Thursday morning as the greatest risk of rapid fire spread
arrives. Although the strongest winds will remain within the 
Sacramento Valley, gusts of 30 to 40 mph are expected to spread 
into Napa County and the Diablo Range south through Santa Clara 
County, with stronger gusts of 50-60 mph possible along the Vaca 
Mountains along Napa County's eastern edge. Meanwhile, daytime 
humidity retention will be very poor with relative humidity values
as low as 10-15%, while overnight recoveries are likewise poor as
RH values top out at 20-30%. Thus, fuels are expected to dry 
rapidly, leading to the elevated fire weather concerns. Also 
important to note that even with the drizzle and light rain coming
through the region, wetting rains (rain totals above 0.1") are 
not expected, limiting any relief that will be realized for the 
midweek period. Elsewhere across the district, conditions remain 
hot and dry, but we're not expecting winds to be as strong as they
are across the interior North Bay. Remember, one less spark, one 
less wildfire.

DialH

&&

.BEACHES...
Issued at 750 PM PDT Tue Jun 9 2026

Long period southerly swell is moving through the waters with buoy
observations suggesting that a swell of around 4 to 6 feet is
coming from 190 degrees, just west of due south, with a period of
around 19 to 21 seconds. The long period swell will result in an
increased risk of sneaker waves and strong rip currents along
south and southwest facing beaches. As a result, a Beach Hazards 
Statement has been issued for the Pacific Coast of the North Bay, 
San Mateo, and Santa Cruz counties through 5 AM on Thursday.
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! 

DialH

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from noon to 11 PM PDT Thursday for CAZ503-504-506-
     508-510-513>515.

     Red Flag Warning from 11 PM Wednesday to 9 AM PDT Thursday for 
     CAZ504-515.

     Beach Hazards Statement through late Wednesday night for CAZ505-
     509-529.

PZ...Small Craft Advisory until 9 PM PDT this evening for Mry Bay-Pt 
     Arena to Pt Reyes 10-60 NM.

     Small Craft Advisory from 9 AM to 9 PM PDT Wednesday for Mry Bay.

     Small Craft Advisory until 9 AM PDT Wednesday for Pt Arena to Pt 
     Reyes 0-10 nm.

     Gale Warning from 9 AM Wednesday to 3 AM PDT Thursday for Pt 
     Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 9 PM PDT Wednesday for Pigeon Pt to 
     Pt Pinos 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

     Small Craft Advisory until 3 AM PDT Thursday for Pt Pinos to Pt 
     Piedras Blancas 0-10 nm.

     Gale Warning until 3 AM PDT Thursday for Pt Arena to Pt Reyes 10-
     60 NM.

     Small Craft Advisory until 3 PM PDT Thursday for Pigeon Pt to Pt 
     Pinos 10-60 NM.

&&

$$

SHORT TERM...KR
LONG TERM....KR
AVIATION...Murdock
MARINE...Murdock

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Prepared by Boulder-Creek.com Weather at: Tue Jun 9 20:30:03 PDT 2026
From the National Weather Service