Temperatures are soaring in Phoenix, which means a lot of airplanes aren't.

Dozens of flights at Arizona's Phoenix Sky Harbor airport were delayed or canceled on Monday and Tuesday, after temperatures reached 120 degrees.

The heat is especially affecting flights on smaller aircraft, particularly flights on Bombardier CRJ planes, an American Airlines spokesman said.

American Airlines contracts regional flights under the American Eagle name to Mesa Airlines and SkyWest, which fly the Bombardier CRJ planes to and from Phoenix. On average, American Eagle has 90 departures and 90 arrivals daily, the American Airlines representative said in an email to CNBC.

As of Tuesday morning, seven flights had been delayed, and 50 flights had been canceled since Monday.

The CRJ planes have a maximum operating temperature of 118 degrees, which was just below the threshold.

Bombardier was not immediately available for comment.