For the seventh day in a row, California's grid operator issued a call for people and businesses to save energy to avoid blackouts as temperatures rose.
The California Independent System Operator (ISO) has asked residents to save energy in the late afternoon and early evening, when the sun sets and the state's large supply of solar-generated electricity diminishes.
The National Weather Service predicts that California's record-breaking temperatures will continue this week, with highs in the interior of the state reaching the mid-40s Celsius.
On Tuesday afternoon, the temperature in Sacramento, the state capital, hit a record high of 46.1 degrees Celsius.
In a video recording that was posted on Twitter, Elliot Mainzer, CEO of the ISO, said, "I know this has been a very long heat wave, and we're not asking you to do even more. But please stay with us and don't use more force than you have to."
As of late Tuesday afternoon, about 20% of the state's electricity needs were being met by solar power.
If power consumption exceeds the grid's energy reserves, the ISO said it will tell utilities to begin enforcing rotating outages. It would be the first time the state has taken such a step since a devastating heat wave in August 2020 prompted power outages in roughly 800,000 households and businesses over two days.
On Tuesday, US electricity prices in California and other western states went up to their highest level since the heat wave of 2020.
Prices for a megawatt hour of electricity went up to US$850 (S$1,200) at the Palo Verde hub EL-PK-PLVD-SNL in Arizona and US$505 at the SP-15 EL-PK-SP15-SNL in Southern California. That was their highest since August 2020, when the ISO last ordered rotating outages and prices hit record highs of US$1,311 in Palo Verde and US$698 in SP-15.