BOULDER CREEK, California: Dozens of lightning-sparked California wildfires grew rapidly on Thursday (Aug 20), forcing tens of thousands of people to evacuate homes in the San Francisco Bay Area.
California has been hit by its worst lightning storms in nearly two decades. Around 11,000 strikes ignited over 370 fires this week, fouling air quality for hundreds of kilometres and stretching firefighting resources to the limit, authorities said.
South of San Francisco, a cluster of lightning-strike fires doubled in size to 16,187ha in San Mateo and Santa Cruz counties, injuring three first responders, forcing 22,000 to evacuate and destroying 20 structures, wildfire authority CalFire reported.
Big Basin Redwoods State Park, California's oldest state park with redwood trees up to 2,000 years old, suffered extensive damage to historic buildings, the state parks department said.
As the fire moved south, the University of California Santa Cruz called for voluntary evacuations from its campus on the northern flank of the coastal city.
To the north, at least nine fires raced through hills in California's wine country about 56km southwest of Sacramento, destroying over 105 homes and other structures.
Collectively known as the LNU Complex Fire, they have doubled in size to 53,000ha since Wednesday, forming a "megafire" 10 times larger than New York's Manhattan island.
"It sucks, everything is gone," Nick Pike told CapRadio in Sacramento after he and three neighbours lost their homes near Vacaville.
A PG&E utility worker died on Wednesday helping first responders, the second fatality from fires after the death of a firefighting helicopter pilot in a crash. At least four civilians were injured in the LNU fire, according to Cal Fire.
Another group of 20 fires, called the SCU Lightning Complex, expanded by nearly a third to around 56,656ha on Thursday some 32km east of Palo Alto.
Record-breaking heat baking the West Coast is caused by a dome of high pressure over the desert east of California that is siphoning off moisture and causing precipitation to evaporate before it reaches the ground, sparking dry lightning.
California has warmed steadily since the beginning of the 20th century, and higher temperatures are blamed for longer and more intense fire seasons that have caused eight of its 10 largest wildfires in the last 15 years.
The American Lung Association warned that the coronavirus pandemic exacerbated health hazards posed by smoky air and extreme heat.
Inhaling smoke and ash will likely worsen the weakened lungs of people infected with coronavirus and undermine the natural defences of those who do not have it, said Dr Afif El-Hassan, a physician spokesman for the lung association.
Governor Gavin Newsom requested 375 fire crews from out of state as California prisoners who normally fight fires were locked down for COVID-19 or released from prison to slow the spread of the virus.
To the east in drought-stricken Colorado, the state's second-largest wildfire in history grew slightly in remote mountains near Grand Junction, about 306km west of Denver.