Californians asked to cut power use as extreme heat approaches

By Brendan O'Brien

(Reuters) - Californians were urged to ratchet down the use of electricity in their homes and businesses on Wednesday as a wave of extreme heat settles over much of the state, stretching tight power supplies to their breaking point.

Temperatures in the most populous state are forecast to climb to well above 100 Fahrenheit (38 Celsius) during the afternoon.

The extreme conditions are the latest sign of the impact of climate change in the U.S. West, where wildfires and severe drought have emerged as a growing threat. As spells of excessive heat become more frequent, the strain on power and water utilities will become more acute, scientists say.

To prevent power outages, residents are asked to turn off lights and appliances and preset their thermostats to 78F (26C). Reducing usage is especially critical from 4 p.m. to 9 p.m. local time (2300 to 0400 GMT), when demand across the state typically peaks and solar power generation begins to ebb.

The heat is also raising the risk of wildfires. The Wishon Fire, a 350-acre blaze in the Sequoia National Forest, was 35% contained. (Graphic: https://tmsnrt.rs/3T9z9BB)

On Tuesday, the U.S. government warned that more drastic cuts in water usage were needed to protect dwindling supplies held in reservoirs that crucial to the well-being of seven Western states.

Two critical reservoirs - Lake Mead and Lake Powell - have fallen to just above one-quarter of their capacity this summer. If they fall much lower, the lakes will be unable to generate hydroelectric power for millions of customers in the West, authorities say.

In the Northern California coastal community of Eureka for instance, a high of 110F (43C) was expected on Wednesday while farther north residents in Electric City, Washington, will see 105F, the National Weather Service said.