Thousands of customers of Avista Utilities lost power during a record-smashing heat wave on Monday and Tuesday when the utility ordered rolling blackouts in Spokane, Wash.

About 9,300 customers lost power on Monday, when Spokane temperatures hit 105 degrees Fahrenheit. Power was cut to about 24,000 customers on Tuesday, as the city hit an all-time high of 112 F.

They were the first heat-related power outages to hit the inland Pacific Northwest in at least 20 years. California last year experienced its first rolling blackouts since the Western energy crisis of 2000/01.

While Spokane-based Avista has not announced further blackouts, it has asked customers to cut back on power use from 1 p.m. to 8 p.m. through at least Friday.

“While we plan for the summer weather, the electric system experienced a new peak demand, and the strain of the high temperatures impacted the system in a way that required us to proactively turn off power for some customers. This happened faster than anticipated. Moving forward, we’re committed to reducing the length of outages and supporting our customers during this time with proactive information to manage through the protective outages that are expected this week,” Avista CEO Dennis Vermillion said in a press release.

Avista blamed Tuesday’s rolling blackouts — averaging about an hour each — on its distribution system, especially transformers, being overloaded.

“I do want to clarify that this was a distribution constraint issue; it’s not a supply-side [issue],” Heather Rosentrater, Avista senior vice president for energy delivery, said during a press briefing Tuesday. “When people think about rolling outages, I think they think about those that they’ve heard about in California or even in Texas and have seen those spread across broad areas in their system.”

 The utility serves about 340,000 electric customers in Washington and Idaho.

Washington state has experienced a record heat wave since Sunday, with Seattle temperatures reaching a record-shattering 108 F on Monday.

In Oregon, where Portland set successive record highs of 112 F and 116 F on Sunday and Monday, about 6,300 customers of Portland General Electric lost power over the weekend because of localized stresses on the distribution system. Power went out for another 3,500 PGE customers in the Salem area on Monday, where the temperature hit 117 F.

No utilities in the region have reported supply shortages during the heat wave.