The National Weather Service on Tuesday declared red flag warnings over a vast stretch of the West, including California, Nevada and Montana, prompted by projected strong winds, high temperatures and drought conditions.

Why it matters: In Northern California, where fuel moisture and flammability are especially conductive to extreme wildfire behavior, multiple communities were ordered to evacuate on Monday night and Tuesday because of the rapidly growing Caldor Fire in El Dorado County.

• The Caldor blaze ignited Sunday and grew to around 6,500 acres Monday. It is currently 0% contained and is threatening at least 2,100 structures, according to the U.S. Forest Service's El Dorado division.
• 242 firefighters have responded to the fire, and extreme fire behavior and structure loss were observed overnight Monday.
• The fire could grow quickly throughout the day and into the evening as strong, shifting winds affect the region, leading to what the National Weather Service is calling "critical" fire danger.

Pacific Gas & Electric (PG&E), California's largest power company, announced plans to cut power to around 48,000 customers in parts of 18 counties in Northern California to reduce the risk of ignition from its equipment.

• The shutoff will primarily affect Butte, Shasta Tehama counties, in which the Dixie Fire — the second-largest wildfire in California’s recorded history — is burning.
• The Dixie Fire, which has torched at least 604,511 acres and is 31% contained, spread northeast Tuesday morning, triggering evacuation orders outside the town of Susanville, which has a population of around 15,000.

The big picture: Western states are in the grip of a prolonged, severe drought exacerbated by human-caused climate change that has exacerbated wildfire activity in recent years.

• Eight of the 10 largest fires in California's history have occurred in the past five years, according to CalFire.
• Studies show human-caused climate change is driving an increase in the likelihood and severity of heat waves and droughts, while also leading to bigger, more intense wildfires.

Go deeper:Excess COVID cases, deaths linked to wildfire smoke in new study