NPS warns visitors not to hike into Grand Canyon because of heat

The canceled flights are part of the airline's regional flight system, and are operated by other carriers that use Bombardier aircraft which are not permitted to fly when temperatures exceed 118 degrees, American said.

PHOENIX — The first day of summer brought some of the worst heat the Southwest U.S. has seen in years, forcing flights to be canceled, straining the power grid and making life miserable for workers toiling in temperatures that reached 120 degrees in some desert cities.

The heat is a serious public health hazard in places such as Phoenix and Las Vegas.

Airbus and Boeing aircraft are able to operate at higher temperatures - 127 and 126 degrees, respectively - so American Airlines flights to cities including Boston, Chicago, Los Angeles, and Denver are still scheduled to take off as planned on Tuesday afternoon.

There could be more cancellations later Tuesday, an airline spokesman said.

The airline is letting Phoenix passengers flying during the peak heat Monday through Wednesday to change flights without a fee.

Extreme temperatures cause a change in air density that makes it more hard for airplanes to take off from the runway, the Daily Mail reports.

American Airlines says its customers can rebook flights or request a full refund by contacting reservations at 1-800-433-7300.

"When that happens we have to rely on our second mechanism, which is sweating", Bhow said.

High pressure is partly to blame for the prolonged expectancy of this heat wave. But Phoenix temperatures are expected to reach 120 degrees on Tuesday. They're all forecast to experience the same warm oven as Phoenix. At that point, the only recourse left for the body to cool itself is sweating.

Lack of overnight cooling is one of the biggest problems during a prolonged heatwave and is often the cause of heat-related illnesses. And temperatures remained high even as night fell: at 9:30 p.m. Monday, temperatures were still topping 109 degrees Fahrenheit.

Flights were also cancelled due to heat in 2013.

Homeless people comprised one-third of heat-related deaths in 2016, according to county records. Last year's heat spell, from June to July, saw an average temperature of 80.3 in Salt Lake City, was the hottest on record. But times have changed, along with temperature extremes.

With high temperatures in the Phoenix area expected to remain around 118 degrees on Wednesday, travelers in the area should expect further cancellations.

  • Joanne Flowers