Crews work to protect areas from ongoing Dixie Fire

Thousands of homes in Northern California remain threatened by the nation's largest wildfire as unstable weather creates a high danger of new blazes erupting across the West.

Weekend thunderstorms across the northern Sierra didn't produce much rain, instead whipping up winds and unleashing lightning strikes that that bedeviled the more than 6,000 firefighters trying to contain the month-old Dixie Fire amid temperatures forecast to top 100 degrees Fahrenheit (38 Celsius).

Gusts of up to 50 mph (80 kph) on Saturday pushed flames closer to Janesville, a town of about 1,500 people just east of Greenville, the small gold rush-era community decimated by the fire 10 days ago.

The Dixie Fire was the largest among more than 100 big blazes burning in more than a dozen states in the West, a region seared by drought and hot, bone-dry weather that turned forests, brushlands, meadows and pastures into tinder.

The U.S. Forest Service said it is operating in crisis mode, fully deploying firefighters and maxing out its support system.

The roughly 21,000 federal firefighters working on the ground is more than double the number of firefighters sent to contain forest fires at this time a year ago, said Anthony Scardina, a deputy forester for the agency’s Pacific Southwest region.

The Dixie Fire has ravaged nearly 867 square miles (2,246 square kilometers) - an area the size of Tokyo, or more than twice the size of Indianapolis. It was 31% contained on Sunday.

More than 1,000 homes and businesses have been destroyed and nearly 15,000 structures were still under threat from the Dixie fire, whose cause has not been determined. Pacific Gas and Electric has said it may have been sparked when a tree fell on its power line.

Smoke also drove air pollution levels to unhealthy or very unhealthy levels in parts of Northern California, Oregon and Idaho.

Climate change has made the U.S. West warmer and drier in the past 30 years and will continue to make the weather more extreme and wildfires more destructive, according to scientists.

IMAGE: AP