More -> https://www.diyelectriccar.com/forums/showthread.php/5-phase-srm-motors-199501.htmlI don't think the ambient temperature matters much, because all modern EV motors run high enough power density that they need active (normally liquid, often oil) cooling; their internal operating temperature can get pretty high, even in a temperate climate.
I haven't noticed anyone monitoring the internal temperature of a PM motor in use, but the builders of the Tesla-powered Cobra race car in this forum have been fighting overheating issues, and have reported internal temperatures of their motor's stator, which should be similar (after all, an induction motor and PM motor can have identical stators). Both rotor designs experience heating. When the internal temperature of the motor is more than hot enough to boil water, it doesn't matter much if the ambient temperature is typical of Alaska or Arizona.
I assume that one of the significant challenges of permanent magnet material design for motors is high-temperature performance, but that seems to have been managed in production EVs. Sorry, I don't know what the magic formula for this is.