398
FXUS66 KSTO 242148
AFDSTO

Area Forecast Discussion
National Weather Service Sacramento CA
248 PM PDT Sat May 24 2025

.Discussion...

.Synopsis...
Mostly dry and periodically breezy weather expected from today
into early next week with temperatures fluctuating between near
and slightly above normal as a more progressive pattern sets up
aloft. Low, but nonzero, mountain thunderstorm chances today,
otherwise, elevated fire weather conditions at times, especially
during breezier periods as low humidity and marginal recovery
persists. Trend toward well above normal temperatures anticipated
by late next week, with Moderate HeatRisk and areas of Major
HeatRisk expected.

&&

.Key Messages...

* Today - Saturday:
 -Probability of South-Southwest Wind Gusts > 30 mph: 40-80%,
  highest across Delta and vicinity area in afternoon/evening
  hours.
 -Marginal humidity recovery expected in onshore flow, although
  some localized areas of elevated fire weather conditions
  possible.
 -Slight, 5-10%, chance of isolated mountain showers/thunderstorms
  this afternoon, primarily south of Interstate 80.

* Sunday - Monday:
 -Stronger weather system to progress toward interior NorCal
  Sunday-Monday.
 -Temperatures to fluctuate around near to slightly above normal,
  with areas of Minor HeatRisk.
 -Primarily dry weather anticipated, although a slight 5% chance
  of isolated showers/thunderstorms possible Sunday over the N.
  Sacramento Valley and Sierra.
 -Breezier onshore winds expected Sunday as the system arrives.
  Probability of South-Southwest Wind Gusts > 30 mph:
  --60-90% throughout the Valley and Delta on Sunday
 -Potential elevated fire weather conditions on Sunday with
  breezier winds expected.

* Tuesday - Friday:
 -Warming trend through much of next week, with the potential for
  triple digit heat in the Valley late next week.
 -Periods of breezy winds and low humidity could bring elevated
  fire weather conditions, especially on Tuesday- Wednesday and
  late next week.
 -Areas of Moderate HeatRisk expected in the Valley through
  Thursday, with the potential for Major HeatRisk in the Valley
  by Friday.
 -Near to record high temperatures possible by Friday.
 -Probability of Valley high temperatures > 90F:
  --Tuesday-Thursday: 60-95%, highest Interstate 80 northward.
 -Probability of Valley high temperatures > 100F:
  --Friday: 45-75%, highest north of Interstate 80.
 -Limited overnight relief expected late next week across the
  northern/central Sacramento and northern San Joaquin valleys.
 -Probability of Valley low temperatures Friday night > 65F:
  40-80%.

.Changes from previous forecast...
 -Thunderstorm chances over the Sierra for Sunday are now less
  than 5%.
 -Elevated fire weather conditions possible on Tuesday-Wednesday
  and again late next week.

&&
.AVIATION...
VFR conditions expected to prevail next 24 hours. Breezy westerly
wind gusts 20-25 kts vicinity Delta through 12Z Sunday, with
southerly winds gusting 15-20 kts in the central/southern
Sacramento Valley from 00 to 09Z Sunday. Otherwise, surface winds
at or less than 12 kts elsewhere. Isolated showers or
thunderstorms over the Sierra 18z Sat-00z Sunday, mainly from I-80
southward. Winds increase after 19Z Sunday, with westerly winds
gusting 20 to 30 kts through the Delta, and southerly winds
gusting 15 to 25 kts in the Sacramento Valley.

&&

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

$$