One of the worst heat waves on record for the western United States is set to peak between the weekend and early next week, bringing a brutal, enduring spell of high temperatures to the Southwest, much of California and parts of the Pacific Northwest.

People use umbrellas to block the sun while waiting to take a photo at the “Welcome to Las Vegas” sign Monday. A searing heat wave gripped large parts of the United States on Monday, with much of the West, parts of the East Coast and some of the Deep South under heat alerts. Wade Vandervort/Las Vegas Sun via AP

An extremely dangerous, unusually long heat wave is intensifying and spreading up the West Coast – and there will be no relief for days.