FXUS66 KMTR 060735
AFDMTR

Area Forecast Discussion
National Weather Service San Francisco CA
1235 AM PDT Wed May 6 2026

...New KEY MESSAGES, SHORT TERM, LONG TERM...

.KEY MESSAGES...
Updated at 1215 AM PDT Wed May 6 2026

 - Warmer and drier conditions mid to late week

 - Well above normal for May with warm to hot temperatures this 
   weekend and early next week

&&

.SHORT TERM...
Issued at 1235 AM PDT Wed May 6 2026
(Today and tonight)

Cool temperatures and cloud cover left over from the recent 500 
mb low continue to linger. Tuesday evening's Oakland upper air 
sounding showed ~ 25th percentile temperatures at 925 mb (2500 
feet) and 850 mb (5000 feet) for early May, just below a newly 
developed temperature inversion aloft. The temperature inversion 
is an early sign of newly warming air aloft with 500 mb high 
pressure beginning to advance in across the forecast area. With 
clearing by late morning and afternoon, daytime highs will climb 
to the 60s coastside and bayside to the 70s to 80 well inland. In 
areas that received recent rainfall, lingering surface to lower 
level water vapor availability combining with peak daytime surface
heating may cause mainly small cumulus clouds to develop today as
well. 

For tonight, post sunset cooling will diminish any small cumulus 
clouds while lower level temperatures steadily warm, strengthening
the lower level temperature inversion. Coastal stratus clouds return
tonight, capped underneath the lower level temperature inversion.
The SFO-SAC pressure gradient remains onshore through today, near
3 mb by late afternoon then decreases to 1 mb by early Thursday. 
Onshore winds will usher stratus inland tonight. Low temperatures
tonight in the 50s and 40s. 

&&

.LONG TERM...
Issued at 1235 AM PDT Wed May 6 2026
(Thursday through Tuesday)

A 500 mb high pressure ridge moves in from the west and northwest
during this time, the ridge flanked on each side by strengthening
troughs assisting in dynamic strengthening (meridional north-south
wave strengthening). Lower to mid level thermal ridging will move
in across the forecast area as well. 500 mb heights will increase
to above normal Thursday through Tuesday, peaking over the weekend
to early next week. By Sunday, Monday and Tuesday recent ECMWF 
forecasts show 850 mb temperatures warming up to 20 to 23 Celsius
which is right around the max moving average on Oakland soundings
for the time of year. This means surface temperatures will become
warm to hot, daytime highs in the 80s to 90s away from any marine
influence. Early next week a few spots in the southern interior
may also reach 100F. We may also get close to a few record highs
at the long term stations. If planning to be outdoors please keep
in mind that moderate HeatRisk will be developing for inland areas
Sunday, Monday and Tuesday.

There have been recent positive anomalies observed in the 
subtropical jet stream winds (stronger than usual) entering the 
southwestern states. Global models, particularly the GFS shows 
strength maintaining in both the polar jet stream and subtropical 
jet stream winds crossing the Pacific during this forecast period.
The larger scale pattern may nudge eastward the aforementioned high
pressure system a little quicker to our forecast area. This means
that late week including Saturday for example may warm up a little
faster than currently forecast. Something to keep in mind. Please
stay tuned to the latest updates.

&&

.AVIATION...
(06Z TAFS)
Issued at 943 PM PDT Tue May 5 2026

Elevated stratus remains locked in over the region, but there a
"sloshy" nature to it as the edges ebb and flow. Not a standard
stratus deck. As such, conf is lower. Through the first few hours
of the TAF will keep it elevated, but then enough cooling
overnight should lower CIGs to MVFR most areas. MVFR through mid-
late Wed AM and then VFR (except HAF). Early return tomorrow
evening for places like MRY.

Vicinity of SFO...VFR with SFO in a bit of a clouds "hole" at the
moment. Expect this to fill in with MVFR developing and then last
through 18-20Z Wed.

SFO Bridge Approach...Solid stratus deck 2500-4000ft.

Monterey Bay Terminals...Elevated stratus lowering to MVFR. VFR
re-developing by early Wed afternoon.

&&

.MARINE...
(Tonight through next Monday)
Issued at 925 PM PDT Tue May 5 2026

High pressure over the eastern Pacific will maintain gentle to
moderate northerly breezes over the coastal waters through early
Thursday. Fresh to strong northerly breezes develop Thursday
afternoon through the weekend leading to locally hazardous
conditions and building seas with steep fresh swell.

&&

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

$$

SHORT TERM...Canepa
LONG TERM....Canepa
AVIATION...MM
MARINE...MM

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Prepared by Boulder-Creek.com Weather at: Wed May 6 02:30:03 PDT 2026