A Red Flag fire warning, the earliest in almost a decade, began Friday night at 11 p.m. and continues through the weekend.
The National Weather Service is tracking strong winds at high elevations and heat with dropping humidity.
The warning applies to the North and East Bay hills as well as East Bay interior valleys.
With drought conditions and a dry winter, fire danger has arrived early.
"When humidity drops, that's what's scary," said Mark Skinner, who monitors three weather stations on his property at 1,000 feet elevation on the Napa - Sonoma County border.
"This evening it's 30 percent, but that will change when the weather event kicks in," said Skinner.
"I've seen it down to 14 percent and in October, I saw it down to zero."
Red Flag conditions usually emerge in late summer and fall, but not this year.
"The drought conditions have really put us in a position we didn't want to be in right now," said Paul Lowenthal, Assistant Santa Rosa Fire Marshal.
"Is there potential we're going to have fires this weekend with the conditions? Absolutely, but hopefully they'll continue to be kept relatively small."
These are normally the months for fuel management -clearing vegetation before it dries out.
Unfortunately much of it already has.
"It puts the hair up on my neck and puts us all at a heightened level of concern," said Nick Luby, Deputy Chief of the Oakland Fire Dept.
"The fire season is getting longer and the rainy season is getting shorter."
This week, Oakland Fire transitioned this week into wildfire response, earlier than ever, but neccesary because of fires popping off in April.
"Tests in the Santa Cruza mountains show the fuel is volatile, almost explosive, and it's what we would expect to see in late summer."
This weekend, the Oakland hills will have park closures and extra fire patrols,- keeping a high profile and watching for fire starts.
"This is the first time I can remember it happening this early," said homeowner Scott Norder, describing precautions in the neighborhood.
"Park cars on your driveway, not on the street, to leave space for emergency vehicles to come through, and clear your defensive space."
Lessons learned 30 years ago in the devastating Oakland Hills fire, and learned again with 2017's Tubbs Fire in the North Bay: better alerts, evacuation plans, and coordination.
"We are better prepared, both as emergency responders and the community as a whole," said Lowenthal.
But survivors of repeat wildfires are rooting for the return of summer fog, already weary this early in the season.
"You think about all the crap we've had to deal with the past year, fires, covid, everyone in town being out of work," said Skinner.
"It's crazy, what else you want to throw at me?"
The Red Flag warning ends at 6 am Monday in most areas, but extends to 6 pm in parts of Solano County.