More than 146 million Americans under extreme heat alerts as dangerous weather fuels outbreak of new wildfires

A fierce heatwave has shattered temperature records across the US west and has been tied to at least four deaths in Oregon, with more heat on the way as dangerous weather fueled the outbreak of new wildfires.

Oregon faced triple-digit temperatures and saw several records toppled over the weekend, including in Salem, where on Sunday it hit 103F (39.4C), topping the 99F (37.2C) mark set in 1960. Authorities in Multnomah county – home to Portland, where temperatures broke daily records over the weekend – said they were investigating four suspected deaths tied to the heatwave.

More than 146 million Americans were under extreme heat alerts on Monday, as both sides of the country cooked. Excessive heat warnings, the National Weather Service’s (NWS) highest alert, stretch across the west, covering parts of California, Nevada, Arizona, Oregon, Washington and Idaho. Areas on the east coast, including Florida, Georgia, Alabama and Mississippi, were also under heat advisories.