Worries swirl California weather could bring ‘critical’ wildfire conditions to U.S.

The interior of California was very hot and dry Wednesday and the forecast called for a risk of fire-starting dry lightning as thousands of firefighters already have their hands full with wildland blazes that have been burning for weeks.

A National Weather Service heat advisory stretched down the Central Valley and through inland Southern California, with an excessive heat warning extending eastward across the desert into Nevada.

The state energy grid operator called for voluntary conservation of electricity from 4-9 p.m. because of expected high demand for air conditioning.

A fire weather watch was issued for Thursday evening through Friday evening in much of the interior of Northern California due to a weather system that is expected to bring a chance of thunderstorms with lightning and erratic gusts.

“The combination of possible dry lightning as well as strong winds with the dry fuels could lead to critical fire weather conditions,” forecasters wrote.

Nearly 15,000 firefighters were making progress on 14 major wildfires and several smaller new fires, the California Department of Forestry and Fire Protection said. They include three of the state’s 20 largest fires on record.

In the northern Sierra Nevada and southern Cascades region, the second-largest fire in California history has scorched nearly 3,732 square kilometres. The Dixie Fire was 59 per cent contained and evacuation warnings were lifted in some areas of Lassen and Plumas counties. More than 1,280 structures have been destroyed, including 688 individual homes.

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To the south in the Sierra near Lake Tahoe, the nearly 340-square-mile Caldor Fire remained 50 per cent contained. Firefighters have had enough success against the state’s 15th-largest fire that residents of the city of South Lake Tahoe were allowed to return home last weekend. With inspections 95 per cent completed, nearly 1,000 structures have been counted destroyed, including 776 single-family homes.

In the mountains of the far north coast, the state’s 18th-largest fire has ravaged nearly 767 square kilometres of the Shasta-Trinity National Forest. The Monument Fire was 41 per cent contained but remained a threat to more than 10,500 structures.

California has experienced increasingly larger and deadlier wildfires in recent years as climate change has made the U.S. West much warmer and drier over the past 30 years. Scientists have said weather will continue to be more extreme and wildfires more frequent, destructive and unpredictable.