Marine Weather and Tide Forecast for Port Costa, CA

DISCUSSION

Mostly clear skies this afternoon as the upper level trough begins to fully exit the region. Near normal max temperatures continue today, with the Valley seeing highs in the mid to high 80s this afternoon.

As the early-week trough shifts into the Great Basin, we'll see winds become stronger and more northerly on Wednesday and into Thursday. As north winds increase, conditions will dry out with daytime relative humidity dropping into the single digits to teens across the Sacramento Valley with limited overnight recovery.
Ensemble guidance and EFI are in good agreement with highest threat across the typical western side of the Sac Valley. Our Red Flag Warning remains in place from 11am Wednesday to 5pm Thursday, and now includes the western foothills along the central and southern Sacramento Valley (in addition to the majority of the Sacramento Valley).

As critical fire weather conditions continue on Thursday, temperatures will also see significant increases as upper level ridging builds along the West Coast. Triple digit Valley highs are forecasted starting Thursday and continuing through at least the early weekend in many locations. Widespread Moderate HeatRisk is expected starting Thursday, with areas of Major HeatRisk on Friday and Saturday. To this point, we have issued a Heat Advisory for the northern and central Sacramento Valley and adjacent foothills from 11am Thursday, June 11, to 11pm Saturday, June 13.
While other areas in the Valley will benefit from the Delta's cooling influence, especially in the evening, it remains important for everyone in interior NorCal to practice heat safety! Stay cool and hydrated, and consider checking in on those more sensitive to heat.

There remains some uncertainty in regards to the rate of cooling into next week, but regardless temperatures should begin to cool again slightly starting Sunday as ridging gradually flattens.

AVIATION
VFR conditions next 24 hours. North gusts 15 to 20 kts in the northern San Joaquin until 07Z Wednesday and west wind gusts 15 to 20 kts in the vicinity Delta until 05Z Wednesday. Elsewhere surface winds 12 kts or less.

North winds increase through the northern/central Sacramento Valley after 15Z Wednesday with sustained winds 15 to 20 kts and gusts 25 to 40 kts. East gusts over the mountains up to 40 kts.

STO WATCHES/WARNINGS/ADVISORIES
Heat Advisory from 11 AM Thursday to 11 PM PDT Saturday for Butte County Below 1000 ft-Central Colusa County Incl. I-5- Central Glenn Co & Interstate 5-Eastern Colusa County-Eastern Glenn County-N. Sac Valley in Tehama County-Shasta Metro-Sierra (Tehama-Plumas) 1000-3000 ft-Sutter/Yuba counties below 1000 ft- W Tehama Co Foothills 1000-3000 ft-W. Glenn/Colusa Foothills 1000-3000 ft-W. Shasta County 1000-3000 ft.

Red Flag Warning from 11 AM Wednesday to 5 PM PDT Thursday for Butte County Below 1000 ft-C. Yolo/NE Solano including Woodland- Central Colusa County Incl. I-5-Central Glenn Co & Interstate 5- Eastern Colusa County-Eastern Glenn County-N. Sac Valley in Tehama County-Shasta Metro-Sutter/Yuba counties below 1000 ft-W.
Glenn/Colusa Foothills 1000-3000 ft-W. Yolo County including Capay/I-505-Yolo / Solano County Hills.