I'm currently flying to SF and we're being routed way north. From Dulles we're heading up to Minnesota, then across to Oregon, before approaching CA from the North. Seems the culprit is a massive high pressure area over the Sierra Nevada's that creating a big windstorm. They call it the Diablo Winds, and it bringing winds of up to 80 MPH from the Sierra Nevada mountains west toward Oakland. They saying it's the worst fire conditions in a generation, and there is already a big fire in Sonoma. 180,000 people are currently under evacuation orders.