FXUS66 KMTR 151803
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1103 AM PDT Sun Mar 15 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 133 AM PDT Sun Mar 15 2026

 - Minor HeatRisk today with temperatures above seasonal averages

 - Early season, long duration heat wave brings record-breaking
   temperatures and Moderate HeatRisk through the week

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

&&

.SHORT TERM...
Issued at 133 AM PDT Sun Mar 15 2026
(Today and tonight)

Satellite imagery is showing a band of stratus setting up at the 
immediate coastal region from Half Moon Bay down through Point Sur, 
with a finger of clouds extending from the Monterey Peninsula into 
the Salinas area. Model output is suggesting that some cloud 
development is possible along the San Francisco Bay shoreline 
overnight, but otherwise the region remains generally clear through 
sunrise with low temperatures across the region remaining in the 
middle 40s to middle 50s. 

Today will mark the start of a major heat wave that will challenge 
or set all time records for the month of March -- more about that in 
the long term discussion -- as an anomalously strong ridge develops 
in the eastern Pacific and crawls into the state. It will certainly 
feel quite a bit warmer across the region as temperatures around 5 
to 15 degrees warmer than those seen yesterday are expected, with 
highs in the 80s forecast across the inland valleys, the middle 70s 
to lower 80s near the Bays, and the middle 60s to middle 70s at the 
Pacific coast. Also note that the shallow marine layer that kept the 
immediate coastline cooler yesterday will further compress or even 
erode away as the ridge takes hold, allowing for substantially 
warmer conditions at the coastal regions. Winds will generally be 
light to gentle with a northerly component to the large scale flow. 

Widespread Minor HeatRisk is expected today, corresponding to a low 
risk of heat-related illnesses for the most sensitive populations, 
including children, the elderly, pregnant women, those with chronic 
illnesses, and people working or living outdoors without adequate 
shelter or cooling. Remember to stay hydrated and allow time to rest 
in the shade during outdoor activities, and never leave children or 
pets unattended in the car!

&&

.LONG TERM...
Issued at 133 AM PDT Sun Mar 15 2026
(Monday through Saturday)

The ridge continues to trek across the state through the early part 
of the work week and will strengthen a little bit as the ridge axis 
begins to enter the Desert Southwest during the middle of the work 
week, where it will stall out for a couple of days. Model output is 
showing a possibility for 500 mb heights at OAK to exceed 5900 
meters, which would set an all time record 500 mb height... for the 
entire month of March.  As noted by the previous forecaster, the 
Wednesday to Friday timeframe is when we expect the warmest 
conditions to occur, when highs in the interior valleys reach the 
upper 80s to the upper 90s and the coastal regions range from the 
lower 70s to the middle 80s. We are even starting to see some areas 
of the Gabilan Range reaching triple-digit high temperatures for the 
Wednesday through Friday timeframe, and NBM probabilistic guidance 
continues to show low probabilities (around 10%) for triple digit 
highs in portions of the northern Salinas Valley, the foothills of 
the Berkeley-San Leandro Hills, and the interior East Bay valleys. 
Low temperatures during this period will range from the middle 50s 
to middle 60s across the lower elevations, to the upper 60s and 
lower 70s in the higher elevations. 

This will be our first major heat wave of the year, where 
temperatures that feel more like late summer heat extend pretty much 
through the work week. Widespread Moderate HeatRisk is expected from 
Monday through Friday, with a moderate risk of heat-related 
illnesses for sensitive populations, while patches of Major 
HeatRisk, corresponding to a high risk of heat-related illnesses for 
the general population, are possible within the higher elevations of 
the Santa Cruz Mountains, the foothills of the Gabilan Range near 
Pinnacles National Park, to the east of Salinas, and the mountains 
surrounding Carmel Valley. To re-emphasize points made by the 
previous forecaster: 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). A Heat Advisory will go into effect on 
Monday across the Bay Area and Central Coast, which will extend 
through Friday at the earliest with some potential for expansion 
into the following weekend. 

In addition, the unseasonably warm heat will help dry the fine fuels 
across the region, elevating the potential for grass fires through 
the week. Offshore winds will remain light to moderate, which will 
help mitigate the growth of any fires that take hold. Anyone who is 
engaging in outdoor activities (including camping, hiking, and 
offroading) should exercise caution when using fires and open 
flames. 

As for the longer term, ensemble model cluster analysis does show 
the ridge flattening as it starts to make its way into the southern 
Great Plains towards the upcoming weekend and beyond. The current 
forecast does show a cooling trend for the upcoming weekend, as 
"extraordinarily hot" becomes merely "pretty hot", but how fast that 
cooling trend takes hold will depend on how soon the ridge moves 
eastwards and how fast it flattens. 

&&

.AVIATION...
(18Z TAFS)
Issued at 1102 AM PDT Sun Mar 15 2026

High pressure will build over the region today, which 
will lead to a week of fairly quiet weather. The forecast for the 
next 24 hours looks to be VFR with high clouds passing over the 
region, though the could be some pockets of fog if the winds go 
light enough and there's enough lingering moisture MVFR to LIFR vis 
is possible late tonight and/or around sunrise. Low to moderate 
confidence in the exact location of fog and mist. 

Vicinity of SFO...Generally VFR conditions will prevail, with onshore 
winds returning by the afternoon. Winds should go to variable or 
weakly offshore overnight, with onshore winds returning again 
tomorrow afternoon. Uncertainty remains if SFO or terminals around 
the Bay will see mist, opted to keep the TAF VFR given the lower 
probabilities at this time. 

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...Mainly offshore flow prevails this morning; 
however, onshore wind is expected to return this afternoon. Winds 
ease overnight and may be light and variable to less than 3KT of 
offshore winds. The question for tonight will be does fog return for 
the Salinas Valley and around the southern portion of the Monterey 
Bay? Models are mixed, with CIGS ranging from VFR to LIFR. Opted to 
go with a slightly persistence forecast, but not as pessimistic 
given high pressure is building and drier air should settle in. 
Moderate confidence for KMRY and KSNS TAFs. 

&&

.MARINE...
(Today through Friday)
Issued at 1102 AM PDT Sun Mar 15 2026

A fresh to strong NW breeze will continue across the outer waters
before the wind speed gradually decreases to a moderate breeze
Monday and continues through mid week. Sea heights will stay
moderate due to a combination of wind waves and low southerly
swell.

&&

.CLIMATE...
Issued at 133 AM PDT Sun Mar 15 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

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

Location 		 

Santa Rosa       91 on March 16, 2004
San Rafael       88 on March 25, 1952
Kentfield        91 on March 28, 1923
Napa             92 on March 17, 1914
Richmond         87 on March 31, 2021
Livermore        90 on March 25 and 26, 2025
San Francisco    87 on March 11, 2005
SFO Airport      85 on March 25, 1952
Redwood City     89 on March 31, 2011
Half Moon Bay    83 on March 31, 2000 and March 17, 2004
Oakland Museum   88 on March 11, 2005
San Jose         89 on March 14, 2015
Salinas Airport  92 on March 14, 2015

&&

.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 Tuesday for Pt Arena to Pt 
     Reyes 10-60 NM.

&&

$$

SHORT TERM...DialH
LONG TERM....DialH
AVIATION...KR
MARINE...Flynn

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Prepared by Boulder-Creek.com Weather at: Sun Mar 15 12:30:03 PDT 2026