FXUS66 KMTR 150500
AFDMTR
Area Forecast Discussion
National Weather Service San Francisco CA
1000 PM PDT Sat Mar 14 2026
...New AVIATION...
.KEY MESSAGES...
Updated at 1205 PM PDT Sat Mar 14 2026
- Above normal temperatures and Minor HeatRisk today
- An early season, long duration heat wave will bring record
breaking temperatures and Moderate HeatRisk through the week
- Elevated potential for grass fires due to warm and dry
conditions and periods of moderate offshore winds next week
&&
.UPDATE...
Issued at 952 PM PDT Sat Mar 14 2026
Surface high pressure is advancing over northern and central
California and into the Great Basin. 500 mb heights are also
steadily increasing with greater thermal ridging developing in
the lower to mid levels tonight through Sunday. Surface pressure
gradients are increasing, ACV-SFO is 6.3 mb and UKI-STS is strong
at 2.5 mb. The WMC-SFO pressure gradient will strengthen tonight
and Sunday morning nearing ~ 10 mb Sunday morning. We're already
today seeing signs of downsloping and warming in the North Bay due
to north to northwest winds. Santa Rosa NWS coop site high temp
peaked well above mid March normal at 79F (not far from today's
record high 82 in 2004). Sonoma County Airport high temperature
was well above normal at 80F.
There is a strong temperature gradient over the northern CONUS,
jet stream with positive west-east i.e. zonal anomalies for early
March and a 500 mb wave pattern including overall strengthening
of a long wave ridge. As advertised strong long wave ridging (with
500 mb heights 590+ decameters) will shift to and become focused
over southwestern U.S. through much of if not all this week. This
is a strong dynamic development that'll place our forecast area
under well above normal warm/hot weather with record high
temperatures. For additional info on the forecast please see the
discussions below.
Equipment report: 00z 03/15/2026 Oakland upper air sounding is
unavailable due to a ground equipment failure. Techs are aware of
the issue. It's uncertain at this time if there'll be a 12z upper
air balloon launch.
&&
.SHORT TERM...
Issued at 1205 PM PDT Sat Mar 14 2026
(This evening through Sunday)
The combination of a shallow marine layer and weak, shortwave trough
is keeping temperatures slightly cooler today. High temperatures
across the interior will be in the 70s with the warmest locations
(generally higher terrain) reaching the low 80s. Coastal
temperatures are forecast to peak in the low to mid 60s. Low
level clouds are currently clearing at a faster rate today than
they were at this time yesterday. This is increasing confidence
that temperatures for the coast will not need to be adjusted
downwards to account for prolonged cloud cover like they were
yesterday. A shallow (500 ft) marine layer is likely to redevelop
again tonight along the coast before upper level ridging
suppresses it next week. This will bring a low potential for fog
along the coast tonight into early Sunday morning. High clouds
are expected to move in across the region this afternoon and
continue into the overnight hours. Fog/low clouds are not
expected to be widespread across the Bay Area overnight but there
may be some patchy instances of stratus/fog directly along the SF
Bay Shoreline. Overnight lows generally stay in the upper 40s to
low 50s across.
&&
.LONG TERM...
Issued at 1205 PM PDT Sat Mar 14 2026
(Sunday night through next Friday)
Sunday marks the start of our heatwave with highs rising into the
mid to upper 80s across the interior and 60s to low 70s along the
coast. High clouds return overnight Saturday into Sunday which
will keep afternoon temperatures a few degrees cooler than
forecast next week. On the synoptic scale, upper level ridging
reaches the West Coast late Saturday/early Sunday and will build
throughout the day on Sunday. This initially results in a 591 dam
upper level high centered just offshore of California. The center
of this high will slowly shift eastward Monday through Wednesday
before strengthening to 594 dam (500 mb heights) and remaining
almost stationary over the Southern California/Arizona border
through late next week.
The overall forecast for the upcoming heatwave with temperatures
running 20-30 degrees above normal remains on track but there are a
few changes to address. Initially, the warmest days were expected to
be Monday through Wednesday but it now appears more likely that
the warmest days will be Wednesday to Friday. This is largely a
result of the ridge restrengthening mid to late next week and
remaining nearly stationary (compared to earlier in the week) over
the desert southwest. The temperature difference between each day
is relatively small and each day will be within 1-3 degrees of
each other. High temperatures will be in the upper 80s to mid 90s
across the interior and upper 70s to mid 80s along the coastline.
The hottest locations will be across interior Monterey and San
Benito Counties, the Santa Cruz Mountains, the North Bay Interior
Mountains, East Bay Hills, and potentially the southern Santa
Clara Valley. Both daily records and potentially all time March
records are still on the table Monday through Friday next week.
Long range guidance suggests we could see these warmer
temperatures extend into next weekend before we see some relief
(still above normal but only by 10-15 degrees) the week after.
There is the potential to break some upper air records at OAK this
week (namely 850 mb temperatures and potentially 500 mb heights).
Probabilistic guidance is showing the potential for portions of
the higher elevations to reach the low 100s late next week. The
most likely areas to break 100 would be the Gabilan Range but the
NBM is showing a low (~10%) chance of portions of the Santa Cruz
Mountains, the southern Santa Clara Valley (Gilroy/Hollister),
and the East Bay Hills reaching 100 as well.
This is our first major heatwave of the year and it is going to be a
marathon. We are primarily expecting Moderate HeatRisk with some
relief overnight from overnight lows in the upper 50s to low 60s.
There are patches of Major HeatRisk (impacts most people) in the
higher elevations of the Santa Cruz Mountains and interior Central
Coast next week. Given the long duration of this heat event,
susceptibility to heat related illnesses will increase throughout
the week. If you are going to be outside for prolonged periods of
time make sure you are drinking plenty of water and allowing time to
rest in the shade. Never leave people or pets unattended in the car.
If possible, avoid going outside during the peak afternoon heat
(approx. 10AM - 4/5PM). Heat Advisories will be in effect for much
of the Bay Area and Central Coast Monday through Friday with some
potential to expand into next weekend.
Expect increased potential for grass fires next week as much above
normal temperatures cure small, fine fuels (grass). Offshore winds
will remain light to moderate which will help mitigate how much any
fires that do develop can grow. If you are participating in any
outdoor activities (camping, offroading, hiking, etc) exercise
caution when using fire and be aware that the risk of grass fires
will be elevated next week.
&&
.AVIATION...
(06Z TAFS)
Issued at 1000 PM PDT Sat Mar 14 2026
Low CIGs are forming along the coast as winds reduce affecting HAF
then MRY slightly later into the night. Spotty CIGs will push into
the bays further into the night, bringing CIGs to OAK and SNS then
SJC into Sunday morning. Cloud cover erodes into the afternoon but
hazy conditions look to form in some of the valleys and along the
coast. Winds build in the late morning and afternoon, but look to
become light into that night.
Vicinity of SFO...VFR through the TAF period. Moderate to breezy
northwest winds linger into the night before reducing. Winds become
light and variable into Sunday morning with some slight reductions
in visibilities. Northwest winds build again Sunday afternoon and
last into late that night before becoming light again.
SFO Bridge Approach...IFR-level clouds look form around the eastern
SF Bay in the early to mid morning, with the potential for some
moving through the approach until the late morning before the clouds
clear.
Monterey Bay Terminals...VFR lasts into the night before winds
become light and LIFR CIGs arrive to MRY. IFR CIGs will be slower to
arrive to SNS, but are in the late night and into early Sunday
morning. These lower CIGs will also be accompanied by reduced
visibilities. VFR returns in the late morning as moderate west to
northwest winds build. Slight haze will be possible through much of
Sunday. Winds become light again Sunday night.
&&
.MARINE...
(Tonight through next Friday)
Issued at 843 PM PDT Sat Mar 14 2026
Fresh to moderate north/northwest continue to produce steep fresh
swell. Wind and seas will ease over the inner water Sunday
afternoon followed by the outer waters on Monday. Wind and seas
are expected to remain relatively calm through the remainder of
the week into next weekend.
&&
.CLIMATE...
Issued at 1205 PM PDT Sat Mar 14 2026
The following are the record high temperatures at the long term
sites for March 15th, 16th, 17th, and 18th.
Location Mar 15 Mar 16 Mar 17 Mar 18
Santa Rosa 88 in 2004 91 in 2004 87 in 1996 84 in 2010
San Rafael 83 in 1972 87 in 1972 84 in 1972 80 in 1996
Kentfield 85 in 2004 86 in 2004 87 in 1914 89 in 1914
Napa 86 in 2004 88 in 2004 92 in 1914 87 in 1914
Richmond 85 in 2004 84 in 1972 83 in 2004 78 in 1996
Livermore 83 in 1972 88 in 1972 87 in 1972 86 in 2004
San Francisco 82 in 2004 85 in 1914 85 in 1914 86 in 1914
SFO Airport 81 in 2004 82 in 2004 82 in 2004 77 in 2004
Redwood City 84 in 2004 84 in 2004 85 in 2004 84 in 2004
Half Moon Bay 74 in 1974 78 in 1972 83 in 2004 75 in 1978
Oakland Museum 85 in 2004 85 in 2004 85 in 2004 81 in 2004
San Jose 82 in 2004 85 in 1914 88 in 1914 87 in 1914
Salinas Airport 83 in 1972 87 in 2004 87 in 2004 84 in 1960
&&
.MTR WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory from 10 AM Monday to 8 PM PDT Friday for CAZ006-
502>506-508>510-512>518-528>530.
PZ...Small Craft Advisory until 3 AM PDT Sunday for Pigeon Pt to Pt
Pinos 0-10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt
Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 AM PDT Monday for Pt Arena to Pt
Reyes 10-60 NM.
Small Craft Advisory until 9 AM PDT Sunday for Pigeon Pt to Pt
Pinos 10-60 NM.
&&
$$
SHORT TERM...Kennedy
LONG TERM....Kennedy
AVIATION...Murdock
MARINE...Murdock
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Prepared by Boulder-Creek.com Weather at: Sun Mar 15 00:30:02 PDT 2026
From the National Weather Service
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