Power transmission lines run through Jacumba Hot Springs, March 9, 2021.

The operator of the state’s power grid warned of an increasing likelihood of power shortages Tuesday unless consumers can reduce their energy use even more than they have so far, as California continued to bake under an unusually long heat wave that has produced record high temperatures.

The California Independent System Operator declared an Energy Emergency Alert 1 for 5-9 p.m. Monday, signaling to utilities and consumers that all resources are committed or forecasted to be in use, and that energy deficiencies are expected.

The ISO also extended a Flex Alert until Tuesday, urging residents to take all possible measures to conserve electricity during the peak hours of 4-9 p.m. for the seventh consecutive day.

“This is an extraordinary heat event we are experiencing, and the efforts by consumers to lean in and reduce their energy use after 4 p.m. are absolutely essential,” said Elliot Mainzer, the California Independent System Operator’s president and CEO.

“Over the last several days we have seen a positive impact on lowering demand because of everyone’s help, but now we need a reduction in energy use that is two or three times greater than what we’ve seen so far as this historic heat wave continues to intensify,” he added.

Grid operators will monitor a host of factors including wildfires and generator availability, and will determine later Monday if the emergency notifications need to be elevated to an EEA 2 or beyond.

An EEA 2 would trigger deployment of emergency tools designed to keep supply and demand for the power system balanced during extreme conditions, potentially freeing up to a few thousand megawatts of additional resources.

If conditions continue to deteriorate, an EEA 3 may be declared. If reserves are then exhausted, the ISO would instruct utilities in its service area to manage rolling blackouts. Utilities make the determination of how best to spread and rotate the outages across their service territory, with the goal of keeping them as short as possible.

“We never want to get to that point, of course,” Mainzer said, “but we want everyone to be prepared and understand what is at stake. We can’t control the weather, but we really can bend the demand curve and get through this successfully if everyone doubles down and reduces their energy use as much as possible.”

Current forecasts predict peak demand at 51,145 megawatts on Tuesday, which would break the record of 50,270 MW in 2006, according to the ISO. Wednesday’s load is forecast at 50,002 MW. The ISO is projecting supply deficiencies of 400 to 3,400 MW between 5 p.m. and 9 p.m. Tuesday.

Consumer and commercial demand response, including Flex Alerts, has been helping to extend tight resources over the past week, with a load reduction of around 1000 MW for each of the past several days.

During the Flex Alerts, residents are urged to take the following power-saving steps:

  • setting thermostats to 78 degrees or higher
  • avoiding use of major appliances
  • turning off unnecessary lights
  • avoid charging electric vehicles

Residents are also advised to pre-cool their homes as much as possible and close blinds and drapes to keep interiors cool.

Southern California has seen temperatures soar above 100 degrees every day since last Wednesday, with little relief in sight until at least Friday.

City News Service contributed to this article.