California heatwave strains power supply and fuels deadly wildfires

Losing power and access to fans and air conditioning could be disastrous for these populations, as well as for disabled residents using powered medical devices.

On Monday, record breaking temperatures of 114F (45C) in Sacramento and 115F in parts of the Central Valley triggered warnings to stay indoors and cool during the Labor Day holiday weekend. Outdoor workers remain at elevated risk this week, authorities warned.

Low humidity and high temperatures also elevated the risk for wildfire, turning brush to tinder. Four deaths were reported over the Labor Day weekend as some 4,400 firefighters battled 14 large fires around the state, with 45 new blazes on Sunday alone, said Anale Burlew, a deputy chief with the California department of forestry and fire protection (CalFire).

In southern California, two people were killed and one injured by the Fairview fire, which started Monday near the city of Hemet, the Riverside county fire department said. Roughly 50 miles (80km) southeast of Los Angeles, the fire had quickly spread to more than 2,000 acres by 11pm, prompting evacuations, and was only 5% contained. Multiple residential structures burned.

The California ISO also has issued a flex alert for voluntary conservation between 4pm and 10pm on Tuesday, making seven alerts in as many days. Residents were urged to keep air conditioners at 78F (26C) or higher during the period and to avoid using major appliances such as ovens and dishwashers. In many areas, the late afternoon and evening are the hottest time of day.

High temperature itself exacerbates pollution, accelerating the formation of ground-level ozone, or smog. In southern California, officials last week issued an ozone advisory due to the heatwave, advising people to stay indoors and avoid physical exertion.

Ironically, unsettled weather also brought the chance of thunderstorms over southern California and into the Sierra Nevada mountain range, with a few isolated areas of rain but nothing widespread. The storms also could produce lightning, forecasters said, which can spark wildfires.