Longest-duration Flex Alert yet issued for Thursday night

Another Flex Alert has been issued for California Thursday, but this one will be the longest-lasting one yet, starting at 3 p.m. to end at 10 p.m.

Heat-weary Californians will be asked for a ninth straight day to conserve energy during high-demand hours. During those hours, people are being asked to avoid using major appliances, turn off all unnecessary lights, unplug unused items, set their thermostats to 78 degrees or higher and use fans for cooling their homes.

Most Flex Alerts have called for Californians to conserve power between 4 and 9 p.m. But a so-called heat dome has kept temperatures across much of California elevated, prompting Cal ISO to declare Energy Emergency Alerts this week that could require rolling blackouts to ease the strain on the power grid.

On Tuesday, the hottest day of the week, demand on the power grid peaked to 52,061 megawatts, "a level we have not seen before in California," according to Elliot Mainzer, Cal ISO's CEO and president. "It was also the highest recorded load for the broader Western interconnection."

There were some power outages in Northern California communities, but Mainzer said statewide rolling blackouts were avoided after Gov. Gavin Newsom triggered an emergency message to cell phones, calling on people to reduce their power usage. Mainzer said Californians responded in force to the message immediately after it was sent.

"We saw between 2,000 to 2,500 megawatts of load reduction, which helped restore our operating reserves and ultimately enabled us to avoid a call for rotating outages," he said. "That made an enormous difference in our efforts to keep the power flowing."

Relief appears to be on the way, however – Hurricane Kay could push rain into Southern California as soon as Thursday, and the National Weather Service is forecasting near to below normal temperatures for most of the state next week.