837
FXUS66 KMTR 070428
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
928 PM PDT Mon Oct 6 2025

...New AVIATION...

.KEY MESSAGES...
Updated at 222 PM PDT Mon Oct 6 2025

 - Warmer and drier conditions through Tuesday, with moderate
   offshore wind expected in the higher elevations

 - Cooler, unsettled weather returns late this week

&&

.UPDATE...
Issued at 850 PM PDT Mon Oct 6 2025

Did some minor edits on the sky forecast tonight as stratus
generally remains confined the coastline of the Central Coast and
Monterey Bay this evening. Clear skies are being observed
elsewhere, which should have/should still allow for good Super
Moon viewing conditions. Expect the stratus to linger around the
coast communities from Santa Cruz south, with stratus slowly
starting to slink it`s way into the Salinas Valley. Uncertainty
remains how far north or inland it might expand given the
easterly/offshore wind component.

&&

.SHORT TERM...
Issued at 222 PM PDT Mon Oct 6 2025
(This evening through Tuesday)

Offshore winds prevail in the higher elevations this afternoon, yet
that remain weak to moderate in strength. This has allowed for
temperatures to rapidly warm into the mid 70s to lower 80s across
much of the region. Slightly cooler conditions prevail along the
immediate coast where onshore winds have returned. Temperatures this
afternoon will peak in the low to mid 70s along the immediate
coastline with low to upper 80s across inland areas. Downtown San
Francisco has around a 14% probability of exceeding 85 degrees F
with southeast portions of the city at around 30%. Places such as
Novato, San Rafael, San Mateo, Redwood City, and Gilroy have a 30-
60% chance of exceeding 90 degrees F.

Temperature begin to cool just before sunset with overnight lows
dropping into the mid 50s to lower 60s across much of the region.
Low clouds and/or fog have the greatest potential for reaching the
San Mateo Peninsula and around the Monterey Bay region late tonight
and into early tomorrow morning. However, any low clouds/fog that do
develop will quickly retreat to the coast by mid morning.

Offshore winds will increase once again tonight, yet are expected to
be weaker than this morning. They will be strongest in the North Bay
and East Bay higher elevations. As such, Tuesday will be equally as
warm as today with the interior warming by a few degrees. However,
coastal locations have the potential to be a few degrees cooler than
today depending on when onshore flow returns.

&&

.LONG TERM...
Issued at 222 PM PDT Mon Oct 6 2025
(Tuesday night through next Sunday)

Onshore flow will return regionwide on Wednesday as an upper level
trough approaches the Pacific Northwest coast. This will result in a
significant cool down with temperatures returning to near or below
seasonal averages. Chances for rain return by early Friday morning
as a frontal boundary approaches the North Bay. The boundary is
forecast to shift southward through the day on Friday and into
Friday night bringing rain chances as far south as the Santa Cruz
Mountains. There remains a great deal of uncertainty on the on
potential for rain through the weekend as there is a lack of
consensus in the overall synoptic pattern. Be sure to stay up-to-
date with the latest forecast information as we get closer to the
weekend.

&&

.AVIATION...
(06Z TAFS)
Issued at 928 PM PDT Mon Oct 6 2025

It`s VFR except along the immediate coast from around Half Moon Bay
to Big Sur, satellite shows areas of fog and stratus /IFR-LIFR/.
The marine layer depth remains near or at sea level under thermal
ridging aloft. The WMC-SFO pressure gradient is 9.7 mb, the SFO-SAC
pressure gradient is 0.2 mb and the ACV-SFO and SMX-SFO gradients
are 2.2 mb to 1.7 mb respectively. At the surface there is a mix
of offshore winds (mainly away from the coastline and bays) and
onshore winds (closest to and along the coastline and bays). Dry
conditions support ongoing VFR except nocturnal cooling tonight to
daybreak Tuesday morning also supports redevelopment of shallow
marine layer fog and stratus /IFR-LIFR/ with local intrusions of
fog and stratus occurring. Additionally a few patches of valley
fog may develop due to radiative cooling. A shallow marine layer
is otherwise still fairly easy to mix out quickly under an early
October sun, as expected Tuesday.

Vicinity of SFO...VFR. West to northwest wind near 10 knots decreasing
and becoming light northeast tonight and Tuesday morning. Wind west
to northwest near 10 knots Tuesday afternoon and early evening.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Satellite and surface observations show
areas of fog and stratus /IFR-LIFR/ around the Monterey Bay. The
current surface winds and transport of fog and stratus is somewhat
reflective of a southerly wind reversal e.g. recent SMX-SFO pressure
gradient is 1.7 mb.

Radiative cooling tonight to daybreak Tuesday will result in
patchy valley fog possibly merging with coastal fog and stratus
/IFR-LIFR/ steered by surface to near surface winds. With respect
to forecast winds, evening winds becoming light and variable to
light southeast tonight and Tuesday morning. Onshore winds 7 to 10
knots redeveloping Tuesday afternoon and early evening.

&&

.MARINE...
(Tonight through next Sunday)
Issued at 850 PM PDT Mon Oct 6 2025

Light to moderate winds accompanied by low to moderate seas will
prevail through Tuesday. A low pressure system approaching from
the north will begin to increase winds and seas mid to late week.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.
&&

$$

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

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