Critical conditions have caused the National Weather Service in Sacramento to declare a red flag fire warning in effect now through noon Friday for much of Northern California.

Expected high winds, mid-summer moisture levels in vegetation and humidities below 15 percent caused the extreme fire danger warning, which includes western Nevada County from 3,000 feet to the Sacramento Valley floor.

The agency also issued a wind advisory this morning lasting through Thursday night. North winds of 15 to 30 mph are expected today in western Nevada County, with gusts up to 40 mph.

Those winds are expected to taper off and begin coming from the east on Thursday, continuing into the early hours of Friday. Temperatures are expected in the high 80s to low 90s through the weekend.