The good news: If you were planning on getting out of here and going to, say, Alaska, your travel plans probably won't be affected.
The cancellations so far are limited to shorter flights headed for places like Flagstaff, Yuma, and Tucson.
As American Airlines explained in a statement today, those flights use Bombardier CRJ regional aircraft, which have a maximum operating temperature of 118 degrees. Tuesday's afternoon temperatures are expected to reach 120 degrees, meaning that those planes won't be able to take off or land at Sky Harbor.
Bombardier spokesperson Bryan Tucker explained, "The CRJ aircraft's certification permits us to operate up to a certain temperature. It doesn't mean the aircraft can't physically operate at higher temperatures than what we are certified for — but this is what the certification limits us to."
Air becomes less dense as temperatures rise, he added, which can affect engine thrust and lift.
Wednesday's temperatures are supposed to reach 119 degrees, so it's possible that more flights will end up getting cancelled. We'll update this story as more news becomes available.
As a precautionary measure, American Airlines is giving passengers the option to rebook their flights for free if they're scheduled to arrive or depart Phoenix between the hours of 3 and 6 p.m.
Travelers whose flights have been cancelled also have the option of receiving a full refund. They're asked to call the reservations line at 800-433-7300.
The good news for anyone looking to get out of town and avoid the heat wave this week? Larger aircraft used for longer flights are less likely to be affected.
Airbus and Boeing aircraft are able to operate at higher temperatures — 127 and 126 degrees, respectively — so American Airlines flights to cities including Boston, Chicago, and Denver are still scheduled to take off as planned on Tuesday afternoon.
A spokesperson for Sky International Harbor Airport said that so far, airport staff isn't aware of any other airlines that have cancelled flights due to the heat. Nonetheless, it's probably a good idea to check the status of your flight before you head to the airport.
Update, 5:30 p.m.: American Airlines reports that we're now up to 43 flight cancellations on Tuesday. An additional seven flights landing in Phoenix on Tuesday afternoon have been delayed.
The cancellations include flights in and out of Los Angeles International Airport Tuesday afternoon, as well as flights to and from a number of smaller airports in the Southwest: Austin, Durango, Bakersfield, Burbank, Fresno, Long Beach, Monterey, Santa Fe, Palm Springs, El Paso, Mazatlan, Santa Barbara, San Luis Obispo, and Ontario, California.
Flights headed to and from Tucson this afternoon have also been cancelled.