A blazing heat wave is gripping the western United States, with temperatures soaring in California, Nevada and Arizona.

Health officials warned people to be extremely careful when venturing outdoors.

The risks include dehydration, heat stroke and burns from concrete and asphalt.

The National Weather Service predicted that temperatures could go as high as 48C in Phoenix, Arizona and Las Vegas, Nevada.

At Phoenix Zoo zookeepers doused elephants with water and fed tigers frozen fish snacks.

The heat in California's Death Valley was expected to reach nearly 54C.

That would be just short of the 56C reading from a century ago that stands as the highest temperature ever recorded on Earth.

The heat is the result of a high-pressure system brought on by a shift in the jet stream.

The jet stream, the high-altitude air current that dictates weather patterns, has been more erratic in the past few years.

Scientists disagree on whether global warming is the cause.

The heat wave is not expected to break until Monday or Tuesday.