Arizona is so hot that flights are being cancelled

Major airlines delayed and cancelled flights out of Las Vegas and Phoenix airports as temperatures hit the high 40s, citing difficulty in operating aircraft in extreme heat - causing plenty of headaches for airlines and travellers alike.

There were four heat-related delays out of McCarran International Airport in Las Vegas on Monday, but none had been reported for Tuesday. On the same date a year ago, the desert resort town reached 122.

States in the southwestern US, such as Arizona, California, and Nevada are having one of their hottest summers on record. This temperature with excessive heat wave is recorded as the highest in twenty years and more in the region's history, which might be life-threatening for many who don't take enough precautions.

The density altitude is the main issue, but there also could be simple heat issues on internal components like seals that might become too soft or even melt at higher temperature, MIT aeronautics and astronautics professor R. John Hansman said.

And, of course, the temperature in Phoenix on Tuesday, when the flights were cancelled, was over 118° Fahrenheit.

Thermal, Calif., southeast of Palm Springs, also set a record for average daily temperature, at 107.5 degrees.

American warned passengers over the weekend that it may have to ground flights during a heat wave that could send the temperature soaring to near 120 degrees (49 Celsius).

On average, Phoenix temperatures for this time of year are generally between 105 and 110 degrees.

Jim Brooks only had to walk 50 yards from his vehicle to the Five Guys burger restaurant in Palm Springs.

Brooks told the Desert Sun newspaper he didn't think lunch would be worth it, and he was hitting himself for leaving his home in nearby Cathedral City where he can stay in the air conditioning.

Mascarenas says though the heat creates a strain on the system, SRP prepares for these situations year-round. That is what American Airlines did during the recent Phoenix heat wave.

"It is tragic when someone dies of hyperthermia since in most every case it could have been prevented", Dr. Michelle Jorden of the county's medical examiner office said in a statement.

In recent days, American Airlines has been forced to cancel more than 40 flights in Phoenix, Arizona.

Those temperatures, however, are forecast for the aptly named Furnace Creek in Death Valley, in California, with some areas expecting new temperature records on Tuesday.

The Tuesday forecast put the temperature in Phoenix at a clement 120 degrees Fahrenheit during the midday peak.

Arizona has been experiencing extreme heat lately, even when compared to usual weather conditions in the state in late June.

Death Valley, California, reached 127 Tuesday and Palm Springs hit 122, tying the degree for the same day a year ago.

Because hotter air is thinner, planes also need more speed to take off and, thus, require more runway.