National Weather Service United States Department of Commerce

Dangerous Heat and Possible Flooding

Dangerous heat will persist across the Southwest U.S. through Saturday with daytime highs of 110-115°F. Extreme Heat Warnings remain in effect. Dangerous heat will build across the southern Plains again beginning this weekend. Heavy to excessive rain over the Carolinas Friday may lead to isolated areas of flash flooding. Read More >

ZOA CWSU Discussion KSFO TAF TDA
AWAITING CWSU INPUT
TAF TDA

KSFO/KSQL METAR
METAR
Area PIREPs
PIREP
   
Satellite Webcams, Ceiling≤030 Prob
Webcams

Click here to reload map


SIERRA 03 Hour Forecast SIERRA 12 Hour Forecast SIGMETs
TANGO 03 Hour Forecast TANGO 12 Hour Forecast
ZULU 03 Hour Forecast ZULU 12 Hour Forecast
Area Forecast Discussion Forecast Maps

260
FXUS66 KMTR 280425
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
925 PM PDT Thu Aug 27 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 125 PM PDT Thu Aug 27 2026

- Slight chance of thunderstorms through Friday afternoon,
especially across the Central Coast

- Cooling trend continues Friday into next week

&&

.SHORT TERM...
Issued at 125 PM PDT Thu Aug 27 2026
(This evening through Friday night)

Looking at satellite imagery, seeing more widespread mid-to-high
level cloud cover spreading across the Central Coast and southern
portion of the greater San Francisco Bay Area. The greatest
potential for high-based convection will be across the Central Coast
as the OAK Upper Air sounding reported MUCAPE (instability aloft)
slightly greater than 400 J/kg. This is also where the CAMs and
higher resolution deterministic models show the greatest MUCAPE
values today through early Friday morning. Thus, have added isolated
thunderstorms to the official forecast for the Central Coast. Further
north across the Bay Area, seeing less threat for thunderstorms, yet
remains a non-zero chance.

The Precipitable Water (PWAT) values increase to around or slightly
above 1.5" across the Central Coast by Friday morning with a greater
potential for wetting rains. However, rainfall amounts are projected
to largely be less than 0.10" throughout this event. Thus, we have
issued a Red Flag Warning for much of the Central Coast including
the Santa Cruz Mountains from 5 AM to 3 PM Friday. Fuels remain dry
from the recent warm and very dry conditions above the marine
influences, especially in areas above 1000 feet in elevation. This
is also where the CAMs have the greatest instability on Friday.
Given the Timber and Plaskett fires ongoing, any lightning strikes
and/or erratic/gusty outflows would make for difficult firefighting
efforts. Will closely monitor the latest forecast models and adjust
accordingly.

As the mid/upper level trough deepens off of the Pacific Northwest
coast Friday evening into Saturday morning, expecting this deeper
moisture plume to shift eastward resulting in PWAT values lowering
to near 0.50". Thus, ending the threat for high-based convection.
The mid/upper level low off of the Pacific Northwest will push
inland Friday night into Saturday, leading to a tightening pressure
gradient which will result in breezier winds Friday and into the
weekend. Thus, wind gusts are forecast to reach 25 to 35 mph along
the coast and through favored gaps, valleys, and passes. This
pattern will also usher in cooler temperatures. Zonal flow develops
over the weekend holding temperatures steadily below normal.

&&

.LONG TERM...
Issued at 125 PM PDT Thu Aug 27 2026
(Saturday through next Wednesday)

A reinforcing trough deepens off of the Pacific Northwest coast by
Monday, allowing afternoon temperatures to be some 5 to 15 degrees
below seasonal averages. The current forecast has the potential for
rain showers returning towards the middle of next week. However, the
evolution of things across the tropical Eastern Pacific remains in
question, mainly in the form of remnant tropical moisture to be
pulled in from the south. Thus, forecast confidence remains low at
this time.

&&

.AVIATION...
(06Z TAFS)
Issued at 925 PM PDT Thu Aug 27 2026

It`s VFR with widespread mid and high level clouds over much of
the forecast area. High based showers have decreased in coverage.
A few light showers/sprinkles reached the ground over the north
Central Coast based on earlier webcam and spotter reports. Increased
cloud cover i.e. water vapor will interfere with and decrease
radiative cooling; coastal stratus and fog will be limited tonight
and Friday.

Vicinity of SFO...VFR. A few showers are possible tonight and/or
Friday. Currently, the 06z TAF advertises vicinity showers (VCSH)
11z-20z Friday. West to northwest wind 8 to 14 knots.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Vicinity showers (VCSH) tonight, with
tempo showers 10z-15z Friday morning and low confidence if showers
will continue during late Friday morning. Winds will be a mix of west
to northwest 5 to 15 knots and light and variable.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 918 PM PDT Thu Aug 27 2026

Northwest breezes gradually diminish to moderate by Monday.
Moderate wind driven seas prevail into next week. A long period
southerly swell impacts our coastal waters by Friday and persists
into the weekend.

&&

.FIRE WEATHER...
Issued at 125 PM PDT Thu Aug 27 2026

One more day of near-critical fire weather conditions above 1000
feet, especially across the Central Coast, as warm and dry
conditions continue above the marine layer inversion and overnight
humidity recoveries remain poor into Friday morning. There still is
a non-zero chance for thunderstorms across the Central Coast today
through tonight. By tomorrow, with the increasing potential for
lightning, we have issued a Red Flag Warning for much of the Central
Coast including the Santa Cruz Mountains from 5 AM to 3 PM Friday
given the low confidence for wetting rains to develop. By Friday
night and into the weekend, the cooling trend will continue and
bring cooler temperatures and likely a deeper marine layer, bringing
progressively more relief to some of the higher elevations.

RGass

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning from 5 AM to 3 PM PDT Friday for CAZ512-516-517-
528>530.

PZ...Small Craft Advisory until 9 AM PDT Saturday for Pigeon Pt to Pt
Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt
Reyes 0-10 nm-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt
Piedras Blancas 0-10 nm.

&&

$$

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

Visit us at www.weather.gov/sanfrancisco

Follow us on Facebook, X, and YouTube at:
www.facebook.com/nwsbayarea
x.com/nwsbayarea
www.youtube.com/nwsbayarea




   Select:      24HR Change/Gradients  |  Forecast Gradients   
OSO001
   Select:      MOS/BUFKIT  |  HREF Ceiling  |  WRF RH  |  WRF Ceiling  |  NBM MOS  |  LAMP MOS   






Yesterday ⇛Visible  ⇛Nighttime  ⇛GeoColor+GLM Today
 
24-Hour Temp Change 24-Hour RH Change

⇛Visible  ⇛Nighttime  ⇛GeoColor+GLM

Webcams