FXUS66 KMTR 301131
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
431 AM PDT Thu Apr 30 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1149 PM PDT Wed Apr 29 2026

 - Warming and drying trend continues into Friday for areas away 
   from the coast

 - Overnight and early morning stratus remains in the forecast as
   the marine layer deepens this weekend

 - Cooler conditions return this weekend with a chance of drizzle
   and/or light rain into early next week 

&&

.SHORT TERM...
Issued at 1149 PM PDT Wed Apr 29 2026
(Tonight through Friday)

Very similar conditions to last night at this time, and very 
similar night ahead. Coastal Stratus is building along the SF 
Peninsula and around Point Reyes. This cloud cover will begin to 
push inland over the next few hours filling around the bays as 
pockets of fog form in the valleys across the region.

Again this is a good indicator of the marine layer staying intact 
despite the ridging pattern to the north. This ridge has been 
responsible for the warming trend for the more inland areas, while a 
cutoff low to the south has allowed for the marine layer stick 
around and keep the coast on the cool side. The pressure gradient 
between the ridge and low has been a big factor in the breeziness 
in the marine environment and the immediate coast.

Thursday sees the marine influence keeping coastal and slightly 
inland temperatures similar to previous days, with a few spots being 
slightly cooler as coastals stratus lingers into the afternoon in a 
few spot. The more inland areas not affected by the marine layer 
will continue the warming trend. Highs in the far interior look to 
peak in the low to mid 80s, and the coast will stay around 60 
degrees, and all the areas in between will stick to the 70s.

&&

.LONG TERM...
Issued at 1149 PM PDT Wed Apr 29 2026
(Friday night through next Wednesday)

Coastal cloud cover will linger into the afternoon again on Friday, 
and the marine layer stays strong, so the coast will stay on the 
cool side. The beginning of a shift in the upper level pattern will 
prevent the North Bay from continued warming, with most areas seeing 
similar highs to Thursday, if not slightly cooler. Other more inland 
areas will see the warming trend peak expect more areas to break 
into the 80s and the mid to upper 80s in the far interior with maybe 
a few spots breaking 90 degrees in southern Monterey Co. 

The pattern change really goes in effect Friday night as the ridge 
pushes east and another low pressure and trough builds along the 
Pacific coast. Higher clouds will build that night, and the 
reduction in pressure will allow  for the marine layer to expand and 
push farther inland. These factors, along with increasing onshore 
flow, will allow for a strong cooling trend through the weekend.

Along with cooling temperatures, the low pressure looks to move 
inland over the Bay Area Sunday night. This will start with drizzly 
conditions early Sunday with chances for scattered light rain 
possible later that night as the low centers over the region. Light 
rain and widespread drizzle chances look to last through most of 
Monday with some potential for the low to slow its momentum and 
offer precip chance into Tuesday before exiting. 

While rain chances are good, overall rainfall amounts will be light. 
Most areas will only see trace amounts to a few hundredths of an 
inch of rain from this system.

Behind it, most models hint at another ridge building quickly in the 
midweek. Cloud cover will erode, the marine layer will compress, and 
temperatures will warm again.

&&

.AVIATION...
(12Z TAFS)
Issued at 431 AM PDT Thu Apr 30 2026

Stratus is a bit more widespread this morning with localized fog 
being reported at STS. For interior airports, stratus and fog looks 
to clear by late morning (17-18Z) while coastal sites may stay 
overcast through the entire day. Confidence is highest that HAF will 
stay overcast today while MRY and SNS look to have a brief period of 
clearing during the afternoon/evening hours. Bumped winds up during 
the afternoon/evening hours to better account for WRF guidance and 
gustier winds yesterday. A deeper marine layer is expected to 
develop tonight which will bring an earlier return of stratus for 
most airports. Initial guidance is supporting a mix of IFR-MVFR CIGs 
tonight but leaned more towards MVFR CIGs in the 12Z TAFs given 
models tendency to overdo IFR-LIFR conditions.

Vicinity of SFO...MVFR CIGs to prevail through late morning before 
clearing through the late evening. Breezy W to NW winds return this 
afternoon. Models support gusts to around 25-26 knots during the 
afternoon/evening hours before winds diminish overnight. MVFR CIGs 
return tonight and continue through the end of the TAF period. Not 
anticipating major reductions in visibility this morning or tonight.

SFO Bridge Approach...MVFR CIGs are starting to fill in across the 
SF Bay but the current stratus pattern remains patchy on satellite. 
High resolution guidance keeps stratus remaining patchy over the bay 
through late morning before clearing. Similar to SFO, stratus is 
expected to be widespread tonight with MVFR CIGs likely to impact 
the bridge approach tonight.

Monterey Bay Terminals...IFR. CIGs have been lingering on the MVFR-
IFR border this morning but IFR CIGs are expected to prevail through 
late this morning. Kept the TAF slightly more optimistic with a 
brief period of clearing late morning/early afternoon at both sites. 
Some models suggest that MRY (higher potential) and SNS could stay 
overcast (MVFR) through the entire afternoon/evening. For now, kept 
with LAMP guidance showing a brief period of clearing before MVFR-
IFR CIGs return overnight.

&&

.MARINE...
(Today through Tuesday)
Issued at 431 AM PDT Thu Apr 30 2026

A fresh to strong northwest breeze continues over the coastal
waters into this weekend. Winds will be strongest over the
northern outer waters where winds will result in moderate seas
building to  between 10 to 12 feet. Winds decrease and seas abate
by late  Saturday with conditions improving through the weekend.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 AM PDT this morning for Pt Arena to 
     Pt Reyes 0-10 nm.

     Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this 
     evening for Pigeon Pt to Pt Pinos 0-10 nm-Pt Arena to Pt 
     Reyes 0-10 nm.

     Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt 
     to Pt Pinos 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.

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

&&

$$

SHORT TERM...Murdock
LONG TERM....Murdock
AVIATION...Kennedy
MARINE...Kennedy

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Prepared by Boulder-Creek.com Weather at: Thu Apr 30 10:30:04 PDT 2026