(Reuters) – Washington state energy company Avista Corp told customers to prepare for more heat-related outages on Tuesday after some lost power Monday evening, as homes and businesses cranked up their air conditioners to escape a brutal heatwave.

The company said outages planned for Tuesday “are a protective measure intended to minimize the customer impact, alleviate strain on the electric system and prevent extensive damage to the system that could result in prolonged outages.”

“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,” Avista CEO Dennis Vermillion said in a news release.

The Pacific Northwest has been gripped by an intense heatwave that has shut down much of daily life for residents.

High temperatures in Seattle, the biggest city in the U.S. Pacific Northwest, will reach 92 degrees Fahrenheit (33 Celsius) on Tuesday, down from a record 104 F on Monday, according to forecasts by AccuWeather. That compares with a normal high of just 73 F at this time of year.

Power prices in the Pacific Northwest for Tuesday eased with the Mid Columbia (Mid C) hub in Washington state down to $146 per megawatt hour (MWh) from a record $334 for Monday.

That compares with an average of $30 per MWh at the Mid C over the past five years (2016-2020).

Avista urged all 400,000 of its power customers in Washington, Idaho and Oregon to conserve energy and warned that many of the roughly 8,000 homes and businesses that experienced outages on Monday could have the same thing happen on Tuesday.

The company said the outages will be targeted during the hours of 1 p.m. and 8 p.m. local time and are expected to last one hour.

Some customers may experience more than one outage with no less than one hour in between outages.

(Reporting by Scott DiSavino; Editing by Paul Simao)