641
FXUS66 KSTO 311923
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
1223 PM PDT Sun May 31 2026

.KEY MESSAGES...

 -Dry and warming weather this week, with areas of Moderate
  HeatRisk, low humidity and periodically breezy winds especially
  late Wednesday into Thursday.

 -Delta breezes starting Tuesday continuing through the week.

&&

.DISCUSSION...

...Monday...
Very interesting upper pattern in place on Monday with a closed
weak upper low over Montana, very anomalous heights in central
Canada with a stronger closed low in the Gulf of Alaska.
California kinda in the middle of all this with short wave
ridging with its axis to the west of us. This will result in dry
and warm conditions in the lower 90s.

...Tuesday...
Above mentioned pattern evolves a bit with Montana low filling and
Gulf of Alaska trough moving a bit to the south and east. This
places the upper short wave ridge more over the top of us and
begins to open us up to onshore westerly flow. Looks like some
delta breezes should kick in by Tuesday afternoon. Temperatures
warm just a bit for another dry day with temperatures in the lower
to mid 90s.

...Wednesday through Friday...
A weaker wave will push across northern California and the Pacific
Northwest from the Gulf of Alaska closed low. This will increase
southerly pressure gradients across the area by Wednesday night
into Thursday for some breezy southerly winds. Drying isn`t super
bad as far as fire weather is concerned but humidities will drop
into the teens during this times. Looking at red flag warning
criteria it may be met a few hours during this time, but overall
not looking too bad right now. We will highlight this in the fire
weather forecast though. Eventually by Friday afternoon, heights
lower as the Gulf of Alaska low pushing into the PacNW.

...Saturday...
Temperatures should cool due to the upper low in the PacNW. Looks
like a fairly good gradient should be in place so breezy
conditions seem likely Saturday but relative humidities should be
reasonable as far as fire weather conditions are concerned.
WMR

&&

.AVIATION...
VFR conditions at TAF sites over the next 24 hours. Decreasing
northerly flow today. Surface winds generally at or below 12 kts,
except in the Delta vicinity with west-southwest winds 10 to 15
kts with gusts to 20 kts from 23Z-06Z and again after 23Z Monday.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
None.

&&

$$