American Airlines will allow temperatures to reach 90 degrees before considering it too hot to board. Airports in Phoenix and Dallas have recorded over 100-degree temperatures this summer.

JetBlue Airways sets that threshold at 85 degrees, after raising it from 80.

Federal regulators have set no uniform standards for cabin temperatures during boarding. 

Keeping the cabins cooler could require airlines to burn more fuel, potentially violating their pledges to lessen greenhouse gas pollution — or to delay boarding until temperatures drop, making it harder to keep flights running on time. 

In July, for example, passengers on a Delta flight bound for Atlanta were stranded on the tarmac for hours in high heat, causing some travelers to get sick and others to pass out. The flight was finally canceled.

Three major U.S. airlines — Delta, United and Southwest — don’t set any maximum cabin temperatures that would cause them to keep passengers from boarding, spokespeople for the companies said.

Other airlines set cabin temperature thresholds that aviation unions consider unacceptable.

American considers a cabin temperature of up to 90 degrees adequate to board passengers, “Customer service will not board passengers if the cabin temperature is above 90°F except in extreme cases,” the document says, adding that the “captain has final authority.”

American spokesperson Amy Lawrence ... would not confirm or comment further on its maximum boarding temperature policy.

The IG report said that in 2013, the American National Standards Institute and the American Society of Heating, Refrigerating and Air-Conditioning Engineers recommended that cabin temperature should not exceed 80 degrees.

https://news.yahoo.com/sweltering-plane-cabins-travelers-newest-090000353.html?.tsrc=1013