When weather gets too hot for planes to fly
While many planes don't have a problem with flying in this temperature, it's higher than the maximum operating temperature for some aircrafts. Because of that American Airlines made the announcement that a number of their flights won't be taking off during the peaks temperature.
Aircrafts affected were some smaller Bombardier CRJ airliners scheduled for regional flights - their maximum operating temperature is just a few degrees lower. (118 F). Bigger aircrafts such as Boeing 747s and Airbus models weren't affected as they have slightly higher maximum operating temperature (126-127F or 53C)
The recorded 120F temperature was just 2 degrees lower than the all-time record that was recorded 27 years ago in June 26, 1990.