Letterhead and timestamp
000 FXUS66 KSTO 052048 AFDSTO Area Forecast Discussion National Weather Service Sacramento CA 148 PM PDT Fri Jun 5 2026For additional details on weather and expected impacts over the next 7 days, please visit weather.gov/sto/briefing.KEY MESSAGES
-One last day of heat today, with Widespread Moderate HeatRisk. Cooling to near normal temperatures starts Saturday, dropping below normal early next week.
-Dry weather except for chances of showers Monday and Tuesday, with the potential rainfall amounts beginning to decrease.
-Breezy afternoon and evening onshore winds through Sunday with low humidity bringing a few areas of elevated fire conditions.
-Potential increasing for gusty north winds and low humidity by late next week. -Temperatures trend above normal late next week.
DISCUSSION
...Main change to the forecast is decreasing rainfall amounts for early next week, with generally light amounts expected. ...
..Today
High temperatures this afternoon to be around 10 degrees above normal, generally in the mid to upper 90s. Winds aloft will be from the west northwest ahead of an approaching weather system from the Gulf of Alaska, which this evening will bring an increased delta breeze and breezy west to northwest winds over the northern Sacramento Valley.
..Saturday and Sunday
The approaching system will knock down the ridge over the weekend, with notably cooler, near normal high temperatures. This means mainly mid to upper 80s for the Valley, Delta and lower foothills. Relative humidities remain low in the Valley and combined along with gusty winds will bring a few hours of elevated fire concerns in the north Sacramento Valley. Winds shift from northwesterly to northerly on Sunday, with afternoon humidity in the Sacramento Valley dropping to teens to single digits, bringing elevated fire conditions. One mitigating factor is that winds peak in the morning hours, so strongest winds are not expected to coincide with the lowest humidity. This system will be dry, with breezy wind and and cooler temperatures the main effects.
..Monday and Tuesday
A secondary trough will move in behind the first for early next week. High temperatures drop below normal, in the low 80s for the Valley., This system has more moisture than the first, but recent ensembles have trended less wet. There are chances for some beneficial light rain in the foothills, mountains, and Valley. Stay tuned as more details become know about this system.
..Wednesday through Friday
Northerly winds increase as the trough shifts into the Great Basin. These winds have been trending stronger recently. Gusty winds and low humidity will bring increased fire weather concerns across the Valley, Delta, and lower foothills especially Thursday. Temperatures trend higher late in the week, with hints of mid 90s to potential triple digit highs in the Valley by the weekend.
AVIATION
VFR conditions with clear skies at TAF sites over the next 24 hours. Northwest surface winds sustained 10 to 15 kts with gusts 15 to 20 kts in the northern San Joaquin Valley and Sacramento Valley in the northern Sacramento Valley through 12Z Saturday. In the Delta vicinity, west winds sustained 10 to 15 kts with gusts to 25 kts through 18Z Saturday.
STO WATCHES / WARNINGS / ADVISORIES
None.