Rheem Valley, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

448
FXUS66 KMTR 200659
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1159 PM PDT Thu Mar 19 2026

...New CLIMATE...

.KEY MESSAGES...
Updated at 1247 PM PDT Wed Mar 18 2026

 - Early season, long duration heat wave continues to bring
   record- breaking temperatures and Moderate HeatRisk through
   Friday

 - Elevated potential for grass fires through the week due to
   warm and dry conditions with periods of moderate offshore winds

 - Gradual cooling trend begins this weekend

&&

.UPDATE...
Issued at 853 PM PDT Thu Mar 19 2026

The forecast remains mostly on track, however adjusted max
temperatures for portions of the South Bay that haven`t been
getting as hot as their surrounding areas, likely due to the
seabreeze not making it as far south as central San Jose and
mixing the warmer inversion temperatures just above down to the
surface. The Heat Advisory will expire at 8 PM PDT tomorrow
evening, and we`re currently not anticipating extending it into
the weekend. Despite the cool down of about 10 degrees area wide
on Saturday, max temps will remain 10-15 degrees above normal
through the extended forecast.

&&

.SHORT TERM...
Issued at 105 PM PDT Thu Mar 19 2026
(This evening through Friday)

Definitely a day of nuanced details and micro-climates around the
Bay Area and Central Coast. In the big picture it`s still hot
around the region with temperatures well above for late March. The
details however show many locations are running colder than
yesterday and some of these locations will fall short of their
forecast high temperature. The shallow marine layer from early
this morning was enough to cause havoc on max temps with any
marine influence. All that being said, did tweak a few
temperatures this afternoon, but didn`t completely give up on hope
for a warm up. A quick shift of the wind direction could allow
for a late day bump in temps. The airmass does support it as the
OAK sounding was 19.55C at 850mb at 12Z this am.

For tonight through Friday...marine layer from this morning has
faded and pretty much dissipated per satellite. Offshore flow is
gradually developing just above the surface. This will persist
overnight and actually strengthen a bit leading to better mixing
and some drying flow in the BL. Hi-res guidance shows this as well
with lower moisture at the surface. Some patchy clouds are
possible near the coast, but thinking less than last night.
Friday will be a transition day as the anomalously upper ridge
begins to slowly ease eastward. 500mb heights may decrease
slightly, but 850mb will likely reach their peak. As such, inland
areas have the potential of seeing some of their warmest temps
yet. Just like today however, coastal areas will be tricky again
with subtle temp differences due to marine influence late in the
day. Will keep Heat Advisory as is for now. Even if a few spots
near the coast/bays fall a little short of forecast highs heat
impacts are a cumulative effect.

&&

.LONG TERM...
Issued at 105 PM PDT Thu Mar 19 2026
(Friday night through next Wednesday)

The large area of high pressure continues its eastward push
Friday night into Saturday as an upstream trough/cold front moves
in. At the surface, local WRF model shows the rebuilding of the
marine layer Friday night. The cold front is expected to push
through day putting an end to the heat wave and bringing much
needed relief. The fropa will bring a 5 to 10 degree drop on
Saturday with an additionally 5 degrees on Sunday. Despite the
temp drop for Saturday and Sunday, temperatures will still be well
above normal for March. Temperatures moderate through the first
half of next week, but stay above normal with zonal flow over the
region. Previous forecast had precip brushing the N Bay around the
25th of March, but latest guidance continues with a drier
solution. If this chance of precip is looking less when does
confidence increase? Longer range ensemble forecast show a few
members producing rain around the beginning of April. As they say,
April showers bring May flowers. We`ll see...

&&

.AVIATION...
(06Z TAFS)
Issued at 951 PM PDT Thu Mar 19 2026

VFR. Model guidance is less confident that a shallow marine layer
will return tonight with the most recent buoy observations
supporting this change. Winds are largely easing with most sites
becoming more variable overnight. Moderate onshore winds (10-15
knots) are expected tomorrow afternoon/evening before weakening
again tomorrow night. Moderate confidence that a shallow marine
layer (around 500 ft) will return Friday night into Saturday.
Current HREF and WRF guidance support more widespread stratus
coverage tomorrow night starting around 06Z (potentially earlier for
coastal sites).

Vicinity of SFO...VFR. Winds ease overnight before moderate onshore
winds return late tomorrow afternoon and continue into the evening.
Initial guidance is suggesting stratus will reach SFO between 09-12Z
Saturday night with the potential for IFR CIGs to develop.
Confidence is currently low to moderate that stratus will make it to
SFO (slightly higher for OAK) but guidance is signaling increasing
potential for the marine layer and stratus to return tomorrow night.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...VFR. Removed the mention of stratus for
coastal sites given that marine conditions are not supportive of it
developing and models have backed off. Confidence is slightly higher
in the marine layer and stratus returning Friday night into Saturday
as a shallow (500 ft) marine layer looks to develop. A SE drainage
wind will develop at SNS early Friday morning before winds shift
onshore for both airports during the afternoon/evening hours.

&&

.MARINE...
(Tonight through next Wednesday)
Issued at 951 PM PDT Thu Mar 19 2026

A gentle to moderate northwesterly breeze continues across the
coastal waters. Northwest winds start to increase tonight across
the outer waters before spreading across the inner waters Friday
into the weekend. Hazardous seas return by Friday night due to
strengthening winds. Gale force gusts are expected across the
outer waters late Saturday into early Sunday.

&&

.CLIMATE...
Issued at 1021 PM PDT Thu Mar 19 2026

The following are the record high temperatures at the long term
sites for March 20th.

Location             Mar 20

Santa Rosa         84 in 2004
San Rafael         82 in 1960
Kentfield          82 in 2001
Napa               86 in 2004
Richmond           81 in 2004
Livermore          87 in 1915
San Francisco      78 in 2004
SFO Airport        78 in 2004
Redwood City       82 in 2004
Half Moon Bay      75 in 2010
Oakland Museum     78 in 2001
San Jose           78 in 2004
Salinas Airport    80 in 1934

The following are the record high temperatures at the long term
sites for the entire month of March.

Location

Santa Rosa       92 March 19, 2026
San Rafael       89 March 19, 2026
Kentfield        91 March 28, 1923
Napa             92 March 17, 1914
Richmond         88 March 18, 2026
Livermore        90 March 25 and 26, 2025
San Francisco    87 March 11, 2005
SFO Airport      85 March 25, 1952, March 17, 2026, March 19, 2026
Redwood City     93 March 17, 2026
Half Moon Bay    83 March 31, 2000 and March 17, 2004
Oakland Museum   89 March 17, 2026
San Jose         89 March 14, 2015
Salinas Airport  93 March 18, 2026

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory until 8 PM PDT Friday for CAZ006-502>506-508>510-
     512>518-528>530.

PZ...Small Craft Advisory from 3 PM Friday to 9 AM PDT Saturday for
     Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm.

     Small Craft Advisory until 9 AM PDT Saturday for Pt Arena to Pt
     Reyes 10-60 NM.

&&

$$

SHORT TERM...MM
LONG TERM....MM
AVIATION...Kennedy
MARINE...Kennedy

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