FIREFIGHTERS BATTLE MAJOR WILDFIRES IN CALIFORNIA

MORE than 2000 firefighters battled a massive wildfire in California on Tuesday as authorities warned record-breaking heat expected by the weekend could spark more blazes.

The so-called County Fire in the northern part of the state had scorched mover than 28,000 hectares in Napa and Yolo Counties by Tuesday and was just five per cent contained, fire officials said.

Authorities late Monday had warned residents in several counties to be ready to flee if fire conditions worsen.

The fast-moving blaze, which has not caused deaths or injuries, erupted last Saturday west of the capital, Sacramento, and quickly spread southward.

The smoke and ash from the flames turned the skies orange and prompted the San Francisco Department of Emergency Management to issue an air quality alert on Sunday.

Elsewhere across the west, fire crews this week were also battling several wildfires in Colorado, Utah, Washington and Oregon.

Picture: AP A helicopter transports water to contain a forest fire In Colorado, where more than 2500 homes were under evacuation orders.