“This heat is even going to outdo what we saw in August,” said Jim Rouiller, lead meteorologists at the Energy Weather Group. “More than 100 high-temperature records are at stake across the West.”

The California Independent System Operator, which runs most of the state’s grid, said Thursday it isn’t expecting blackouts. But as of Friday afternoon, the ISO expected Sunday demand to peak at nearly 48 gigawatts. During the Aug. 14 blackout, the peak was 46.8 gigawatts.

“If that forecast is realized, Sunday would be the highest-load day we’ve seen so far this summer,” said BloombergNEF analyst Brian Bartholomew.

Electricity prices for delivery Saturday evening into Southern California jumped to $800 a megawatt-hour, according to data from the grid operator. That’s an indication of tightening supplies as solar production tapers off. Spot prices on Friday briefly jumped to the highest level in more than a year.

For now, the grid operator is urging consumers to dial back their air conditioners and asking power generators for extra electricity supplies. California Governor Gavin Newsom on Thursday signed an emergency order freeing up extra electricity supplies.

Cooling degree days — used to estimate energy demand — over the weekend are forecast to reach record highs, according to BloombergNEF analyst Jade Patterson. If that happens, electricity consumption could breach last month’s heat wave that sent natural gas prices to $13.27 per million British thermal units.

Many heat records for the date could fall across California, Arizona and Nevada through the weekend before the worst of it begins to subside Tuesday and Wednesday, said Rich Otto, a forecaster with the U.S. Weather Prediction Center.

A front from Canada bringing cooler air will dive into the western U.S. breaking the worst of the heat but bringing wind with it that can raise the risk of wildfires, Otto said.