FXUS66 KMTR 092245
AFDMTR

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

...New KEY MESSAGES...

.KEY MESSAGES...
Updated at 345 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

 - 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.

&&

.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...
(18Z TAFS)
Issued at 1133 AM PDT Tue Jun 9 2026

Lingering MVFR ceilings are making their way out of the region by 
this afternoon. Widespread VFR conditions are also expected to 
prevail by the afternoon through the TAF period. W to NW winds 
increase to a moderate breeze (10-15kts) with a few terminals 
experiencing ~20kt gusts. Winds begin to ease by sunset and continue 
to diminish overnight.

Vicinity of SFO...VFR through the TAF period. High confidence that 
westerly winds will increase by the early afternoon with some 
embedded gusts above 20kts. Winds are expected to diminish overnight 
and increase back to moderate breezes by Wednesday early afternoon.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...The remaining low-level clouds are 
currently mixing out as onshore winds increase by the early 
afternoon. NW winds are expected to begin to ease by sunset and 
remain light overnight. Low confidence on an MVFR ceiling this 
evening given how dry the atmosphere is (and will continue to be) 
in this post-frontal environment. VFR all the way! 

&&

.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 1208 AM 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. 
Although the strongest winds will remain within the Sacramento 
Valley, gusts of 25 to 35 mph are expected to spread into Napa 
County and the Diablo Range south through Santa Clara County, with 
stronger gusts of 40-50 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.

We are continuing to monitor the potential for fire weather products 
to be issued for the interior mountains of the North, East, and 
South Bays for Wednesday and Thursday. At present, conditions are 
right on the edge of critical fire weather criteria, but the 
confidence isn't there at this point to pull the trigger on any 
warnings. The day shift will reevaluate the fire weather forecast 
for Wednesday and Thursday and in collaboration with neighboring 
offices, will be in a better position to determine the extent of 
necessary products. Regardless of whether any products are issued 
across the interior, elevated to near critical fire weather 
conditions are still forecast and care must be taken to avoid 
starting a fire that could spread rapidly. Remember, one less
spark, one less wildfire.

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.

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 from 9 PM this evening to 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...Navarrete
MARINE...Murdock

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Prepared by Boulder-Creek.com Weather at: Tue Jun 9 16:30:03 PDT 2026