Overview
- Midweek monsoon moisture shifted east, leaving lower humidity and gusty westerly winds that increased near‑term wildfire danger across Northern California.
- Pacific Gas and Electric warned of potential public safety power shutoffs for parts of Alameda, Contra Costa and Marin counties on Wednesday and Thursday to reduce the chance of utility‑caused ignition.
- Forecasters reported valley heat and 'Impact Day' conditions earlier in the week but said a strengthening Delta breeze Thursday and Friday will push marine air inland and cut most valley highs to the low‑ to mid‑90s.
- Models show a developing uncertainty for the weekend because Tropical Storm Elida could feed a renewed pulse of monsoon moisture northward, which would raise humidity and boost the chance of Sierra and mountain thunderstorms Sunday into Monday.
- Residents should prepare for short‑term power interruptions and stay ready for fire or storm impacts, and understand that the Delta breeze is an onshore flow that cools inland areas by funneling cooler coastal air through gaps into the Central Valley.