Wall of dust 8,000ft high sweeps across the desert and engulfs US city

A MASSIVE dust storm descended on Phoenix, Arizona on Tuesday night, delaying flights and cutting visibility as strong winds toppled trees and caused power cuts for thousands of residents across the valley in which the city sits.

The storm was part of the Arizona monsoon season, which usually starts in the middle of June and lasts until the end of September.

The dust cloud that moved across the Phoenix valley had formed in an afternoon storm in the Tucson area, and then rolled north across the desert before sweeping over the city like an enormous wave, said US National Weather Service meteorologist Paul Iniguez.

Radar data showed the storm's towering dust wall had reached as high as 8,000 to 10,000 feet, he said.

"This was pretty significant," Mr Iniguez said. "We heard from a lot of people who lived here for a number of storms and this was the worst they'd seen."