Amid sweltering heat, dozens of flights canceled in Phoenix Temperatures in Phoenix are expected to hit a high of 120 degrees today.

 -- With sweltering temperatures in Phoenix today, American Airlines has canceled 43 flights at the city's Sky Harbor International Airport — just as broiling residents are likely wanting to get the heck out of Dodge.

That's because American's regional aircraft, the Bombardier CRJ, has a maximum operating temperature of 118 degrees Fahrenheit at Phoenix's elevation.

Experts say hot air affects engine output and increases the required plane speed and runway length for takeoff — and since the CRJ, a Canadian plane, has not been tested under those conditions, it hasn't been verified as safe in temperatures above 118 degrees.

American's bigger jets, from Airbus and Boeing, have higher maximum temperatures for operation (127 and 126 degrees, respectively) and aren't affected by Phoenix's forecast.

Delta was forced to cancel three flights because of weather conditions at Sky Harbor: two on Bombardier CRJs and one on another regional jet, the Embraer 175. United had to delay one of its flights, on an Embraer 175.

Temperatures in Phoenix are expected to hit a high of 120 degrees today, according to the National Weather Service.