FXUS66 KMTR 062320
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
420 PM PDT Mon Apr 6 2026

...New AVIATION, MARINE...

.KEY MESSAGES...
Updated at 1237 PM PDT Mon Apr 6 2026

 - Cooler seasonal to slightly below normal temperatures this week

 - Beneficial rain arrives midweek and lasts into the weekend

 - Slight chances for thunderstorms Thursday and Friday afternoon

&&

.SHORT TERM...
Issued at 1237 PM PDT Mon Apr 6 2026
(This evening through Tuesday)

The marine layer redeveloped overnight with widespread stratus 
observed across the Bay Area and Central Coast due to a weak 
shortwave trough moving into California. We are still looking at 
cooler temperatures today with highs in the low to mid 70s across 
the interior and 60s closer to the coast. Light, onshore winds 
continue with locally breezier conditions across the higher 
elevations and mountain gaps/passes. Widespread stratus is expected 
again tonight with the marine layer deepening to around 1500 ft. 
Most of the Bay Area and coastal Central Coast can expect to wake up 
to overcast conditions again with patchy fog possible in the North 
Bay and South Bay Valleys. Clearing times tomorrow will be similar 
to today with stratus coverage gradually dissipating over the course 
of the morning. High temperatures linger in the 70s across the 
interior and 60s along the coastline again on Tuesday. Shortwave 
ridging briefly builds in during the day on Tuesday before the ridge 
quickly progresses eastward Wednesday. Stratus returns Tuesday Night 
but shortwave ridging will start to compress the marine layer and 
keep stratus confined closer to the coast.

&&

.LONG TERM...
Issued at 1237 PM PDT Mon Apr 6 2026
(Tuesday night through next Sunday)

Brief shortwave ridging Tuesday into Wednesday will allow 
temperatures to warm slightly on Wednesday but only by a few 
degrees. High temperatures will be in the mid to upper 70s across 
the interior, low 80s across the interior Central Coast, and in the 
60s along the coast. This will be short lived as our promised cool 
down truly begins Thursday and continues into the weekend. A deep 
upper level cut-off low will approach the West Coast on Wednesday 
and will push Tuesday's shortwave ridge eastward. This low pressure 
system is a cold core low from the Gulf of Alaska and is bringing a 
cooler air mass (850 mb temperatures around 6-8C) with it. The mean 
850mb temperature for early to mid April is around 7-8C so this 
colder air mass is really only bringing us back to more seasonal 
temperatures. We do continue to see colder air being advected in 
over the weekend with 850 mb temperatures dropping to around 0-1C. 
This would be around the 10th percentile for 850mb temperatures for 
this time of year and signals below normal surface temperatures are 
more likely. What does that mean at the surface? Temperatures will 
first cool to more seasonal values on Thursday with highs in the 60s 
to low 70s. Friday into the weekend, high temperatures become 
seasonably cool in the 60s with most spots running around 2 to 5 
degrees below normal. Overnight low temperatures will also 
experience a cooling trend with lows gradually cooling from the 50s 
to mid to low 40s. Portions of the interior Central Coast may see 
low temperatures dropping into the upper 30s starting Sunday.

Temperatures are only part of our weather change up, however, so now 
we turn to the much anticipated precipitation forecast for the 
upcoming week. As our cut-off low arrives, it will bring a fairly 
persistent stream of moisture with it. PWAT values are around 0.8-
0.9" with the slow movement of the low southwards along the 
California coast keeping the moisture training over the Bay 
Area/Central Coast. Coastal drizzle becomes more likely Wednesday 
night into Thursday morning with scattered showers moving in 
throughout the day on Thursday. Showers then continue through the 
weekend thanks to the slow movement of the low. Precipitation totals 
have increased slightly with most of the lower elevations seeing 
between 0.25-0.35" of precipitation. The higher elevations remain 
the big winners with up to 0.75" of rain expected. The highest peaks 
of the Santa Cruz Mountains and the Santa Lucia Range will see 
anywhere from an inch to an inch and a half of rain. Rainfall 
remains beneficial and is helping to reduce near term fire concerns. 
Locally gusty winds are expected directly along the coastline and 
across the higher elevations but conditions are not forecast to meet 
Wind Advisory criteria. 

Thunderstorms are still possible Thursday afternoon and again Friday 
afternoon. The setup now looks more favorable for thunderstorms on 
Friday (20-25%) rather than on Thursday (10-15%). MUCAPE values 
still look good but low level shear remains minimal. If any 
thunderstorms do develop the most likely hazards would be locally 
heavy rain, gusty winds, and the potential for small hail. 

&&

.AVIATION...
(00Z TAFS)
Issued at 419 PM PDT Mon Apr 6 2026

Patchy MVFR stratus at the immediate coast at present, with the rest 
of the region currently VFR. Moderate onshore winds persist through 
the evening hours, with gentle winds overnight before onshore flow 
resumes Tuesday afternoon. Model guidance is suggesting that the 
inland expansion of MVFR-IFR stratus might begin much sooner than 
the previous forecast indicates, perhaps by 03-04Z across SFO and 
OAK. Will monitor the evolution of stratus over the next few hours 
to see if this plays out. Stratus is expected to persist through the 
night and retreat to the immediate coast on Tuesday morning. Low 
confidence that HAF might scatter out sometime on Monday afternoon, 
but for now the TAF reflects the terminal being socked in.

Vicinity of SFO... VFR at present with breezy northwest winds. 
Moderate confidence that MVFR-IFR stratus will begin to flow through 
the Golden Gate in the next few hours, impacts to the terminal 
beginning around 02-04Z. Stratus will dissipate Monday morning 
around 18-20Z, with breezy west-northwest winds in the afternoon. 
Towards Monday night, not seeing an impressive signal for stratus 
development with winds staying gustier into the end of the TAF 
period.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals... VFR at the terminals, with some lingering 
clouds in the vicinity of MRY. Model output depicts the stratus 
layer redeveloping over the terminals in the next couple of hours, 
with IFR ceilings through the night and dissipating late Tuesday 
morning. Breezy northwest winds at the terminals will diminish in 
the evening hours, becoming gentle overnight before moderate winds 
resume Tuesday afternoon.

&&

.MARINE...
(Tonight through next Saturday)
Issued at 419 PM PDT Mon Apr 6 2026

High pressure off the California coast will maintain light to
moderate breezes across the coastal waters through the week.
Locally fresh breezes will develop offshore of the Big Sur coast
this afternoon with the strongest wind near and south of Point
Sur. Unsettled weather returns mid to late week, bringing light
showers, a slight chance of thunderstorms, and moderate seas.
Winds increase next weekend with a fresh breeze expected over
portions of the coastal waters.

&&

.MTR WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...Small Craft Advisory until 9 PM PDT Tuesday for Pt Pinos to Pt 
     Piedras Blancas 0-10 nm.

&&

$$

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

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Prepared by Boulder-Creek.com Weather at: Mon Apr 6 16:30:02 PDT 2026