Extremely high temperatures on the ground in Phoenix have lead to mass cancellations of flights out of Sky Harbor International Airport and trends like this might continue with soaring heat in the American Southwest.

Larger jets like the 757 aren't as affected by high temperatures on the ground, but smaller ones like the Bombardier CRJ aircraft are, which made American Airlines cancel 20 regional flights out of the now sweltering Southwest.

Air temperature on the ground can affect takeoff performance. Warmer air is less dense than cooler air, and planes would need longer runways to build more speed to lift themselves into the air. If it gets hot enough, airlines will attempt to mitigate the risk by cancelling flights and reimbursing or rebooking stranded travelers.

It has apparently getting hot enough for the National Weather Service to issue several weather advisories about the heat in the Southwest region being "extreme even for desert standards."

"It takes a lot for the weather service to put out excessive heat warnings for that part of the country, so you know it's going to be pretty darned hot," said Ari Sarsalari, a meteorologist for The Weather Channel.

June is normally the hottest month in the desert but this summer could be unprecendented. Pheonix has reached 118 degrees Monday and could easily break its 122 degree record into Tuesday, leading to more flight cancellations and heat advisories through out the region.

VIDEO: Man Cooks Himself Lunch With Only Arizona Heat