© Reuters. FILE PHOTO: California power lines are shown ahead of a major wave in 2020 in Carlsbad, California, the United States, Aug 17, 2020. REUTERS / Mike Blake / File Photo
By Dan Whitcomb and Scott DiSavino
LOS ANGELES (Reuters) – Much of the western United States baked for a third day Wednesday under a punishing heatwave that has already broken temperature records, triggered health warnings and weighed on power grids.
Although a shift in the weather has brought some relief to northern states, including Montana and Idaho, the worst was yet to come, said National Weather Service meteorologist Eric Schoening.
"We are in a prolonged heat wave in the western United States," said Schoening. "Over the southwestern desert, which extends into California, we're still raising temperatures for the rest of the week."
Salt Lake City, Utah, hit 107 degrees Fahrenheit (42 degrees Celsius) Tuesday, its all-time high since records began in 1894. Phoenix, Arizona hit a record for that date of 115 degrees and Needles, California hit 121 degrees, also setting a daily record.
The National Weather Service has warned of excessive heat in the western United States that such temperatures can be dangerous. By Wednesday afternoon, no fatalities had been reported from the brutally hot weather.
"Try not to spend too much time outside during the hottest part of the day. Wear light clothing, stay hydrated," Schoening said, adding that residents "keep an eye on pets, check on the elderly and not leave anyone should, including children ". or pets in hot cars. "
The weather service also warned of high risk of fire in Arizona, California, Nevada and Utah. Large forest fires burned Colorado and Arizona.
The unusually violent late spring heat wave was caused by a high pressure ridge that formed over southwestern deserts, say meteorologists with the Meteorological Service, and could not be directly attributed to global warming.
"But studies show that over time we will see more of these abnormal events as the climate changes and it gets warmer," Schoening said.
The brutal heat led to an increase in electricity demand as residents turned on air conditioners and fans. Power grid operators in Texas and California, the two most populous US states, called for energy savings.
California and Texas both imposed rolling blackouts last year to avoid a grid breakdown, California due to the heat in August 2020 and Texas in February 2021 after a deep frost that left millions without heat.
The California electricity grid operator warned that the greatest load could come on Thursday after dark falls and solar power is no longer available.
Much of the southwestern United States is also affected by a drought
that cut the hydropower supply. Rivers are drying up, ranchers are selling cattle and authorities fear another intense forest fire season.
Forest fires burned more than 17,000 square kilometers of land in 2020 and destroyed hundreds of California homes during a particularly violent season of fire.
California's Independent System Operator (ISO), who operates most of the state's electrical system, predicts that electricity demand this week would exceed supply and reserves for several days. Electricity grids have reserves ready to ensure reliability in the event that something goes wrong with a generation plant or transmission line.
The Electric Reliability Council of Texas (ERCOT), which operates most of the state's electricity system, predicted that demand in the coming days would break the June record set on Monday.
In Houston, the largest city in Texas, mercury is set to hit the upper 90s on Wednesday and Thursday, about five degrees higher than usual, according to AccuWeather.