As a prolonged record-setting heat wave tightens its grip on the West, millions in California are being told for a fifth day to cut energy consumption amid concerns about a strained power grid.   

  More than 45 million people across the western US are currently under extreme heat warnings and advisories.  Many are spending the holiday weekend in triple digits, including in California, Oregon and Idaho, according to the National Weather Service.   

  Many cities have already seen record-breaking hot temperatures.  Boise, Idaho, dipped below a record high of 101 degrees on Friday, tying its previous daily record set in 1950. Salt Lake City reached 103 degrees on Saturday, surpassing the previous record of 98 set in 2017 .In Southern California, Burbank set a new monthly high for August at 112 degrees on Wednesday.   

  The dangerous heat wave is expected to continue to affect much of the West over the weekend and into the middle of the week.  Temperatures will range from 15 to 20 degrees above normal with highs over 100 degrees.   

  Temperatures up to 110 degrees with overnight lows in the 80s are possible Sunday.   

  In California, where some areas are seeing blistering temperatures 10 to 25 degrees above normal for this time of year, the heat is already increasing demand for power and straining the power grid.   

  And the hottest temperatures are yet to come, Sarah Rogowski with the National Weather Service said in a Saturday update.   

  California’s Independent System Operator — which manages 80 percent of the state’s electricity grid — extended another Flex Alert through Sunday, asking residents to conserve electricity to protect the power grid because of the potential for power outages.   

  Despite the heat, Californians are urged to set thermostats to 78 degrees or higher, avoid using large appliances and turn off all unnecessary lights from 4 p.m.  until 9 p.m.  of Sunday.  The operator asked residents to pre-cool their homes before 4pm   

  “Additional Flex Alerts will likely be called as the heat will only intensify through Tuesday, with little relief from the triple-digit temperatures seen in the coming days,” the California Independent System Operator said in a news release.   

  Over the past three days, the electric utility has received the most power demand it has seen since September 2017, Elliot Mainzer, president and CEO of the California Independent System Operator, said during a news briefing Saturday .   

  “These last few days are likely to be a dress rehearsal for what is going to be a much more stressful set of conditions here,” Mainzer said.   

  He stressed that residents’ compliance with the alert is critical to ensure there are no blackouts.  “That response can be the difference between the light staying on or not,” Mainzer said.   

  NV Energy, which serves more than 1.5 million homes and businesses across Nevada, has also asked residents to reduce their electricity use to avoid straining the power grid between 5 p.m.  to 8 p.m.   

  Hot temperatures across the region, combined with low relative humidity, also mean increased fire risk.  Parts of Northern California, southeastern Oregon, northwestern Nevada and southwestern Idaho are under critical fire weather conditions, according to NOAA.   

  The National Weather Service in Spokane, Washington, said regional and local wildfires are degrading air quality.

A picture is worth a thousand words, but a gif is worth much more. Multiple regional and local fires are causing air quality degradation. Red flag warnings begin today at 12 p.m. PDT. #CedarCreekFire #BoulderMountainFire #EneasPeakFire #RussellMountainFire #wawx #idwx #orwx pic.twitter.com/Sou7UEiySn — NWS Spokane (@NWSSpokane) September 2, 2022 Two Northern California wildfires that broke out Friday grew rapidly, forcing both evacuations.

  “Over the last several days, we’ve definitely seen a steady increase in the number and size of wildfires burning across California,” Cal Fire Chief Deputy Chief Chris Anthony said during Saturday’s news conference.   

  The Mill Fire in Siskiyou County had burned about 4,254 acres as of Saturday night and had destroyed 50 structures.   

  In the same county, the Mountain Fire grew to 4,812 acres.   

  Further south, the fire in Los Angeles County was at 5,208 acres Saturday night and 87 percent contained, according to an update from the Los Angeles County Fire Department.  The blaze destroyed two structures and threatened hundreds of others.   

  The heat dome causing the heat wave will slowly spread eastward across the central and northern plains by midweek.  More than 150 high temperature records could be set or tied by Thursday, according to CNN meteorologist Derek Van Dam.   

  While high temperatures are expected to continue into the middle of the week, with little relief overnight, cooler temperatures are expected on Thursday.   

  “There is some relief with … cooler temperatures reaching the northern parts of the state by Thursday, moving further south by Thursday and Friday,” Sarah Rogowski of the National Weather Service said Saturday in a briefing.   

  “However, temperatures remain above normal and this is expected to continue into the middle of the month,” he added.   

  Extreme weather events, including heat waves like today’s, are happening more often and will continue to be more frequent and more intense due to the effects of human-caused climate change, scientists have warned.