Thousands of people were forced to evacuate in the midst of a heat wave and a pandemic on Thursday as lightning-sparked firestorms raged through dry brush, grass and chaparral around San Francisco Bay.
An estimated 11,000 lightning strikes, mostly in northern and central California, ignited more than 370 individual fires this week, spawning nearly two dozen major conflagrations that threatened thousands of homes and prompted mass evacuations.
This is the most number of lightning strikes to rake California in more than a decade.
As of Thursday, the biggest fires had collectively scorched more than 500,000 acres, an area twice as large as New York City’s entire land mass. Scores of homes and other buildings were left in ruins, and at least two people have lost their lives.
A utility worker died on Wednesday while on duty helping clear electrical hazards for first-responders. Earlier the same day, the pilot of a firefighting helicopter contracted by the state was killed in a crash during a water-dropping mission in Fresno County.
The blazes raged amid a record-breaking heat wave that has baked California since last Friday, resulting from a dome of atmospheric high pressure hovering over the American Southwest.
Meteorologists say that the same high-pressure ridge has also been siphoning moisture from remnants of a now-dissipated tropical storm off the coast of Mexico and creating conditions rife for thunderstorms across much of California.
Most of the precipitation from those storms evaporates before reaching the ground, however, leaving dry lightning strikes that have only added to what was already a volatile wildfire season.
The American Lung Association warned on Thursday that the coronavirus pandemic has considerably heightened the health hazards posed by smoky air and extreme heat.
Inhaling smoke and ash can worsen the weakened lungs of people with COVID-19 and undermine the natural defenses of those who do not have it, said Dr Afif El-Hassan, a physician spokesman for the lung association.