Paul Beckwith did a video about Iran and other areas where temperatures exceeded survivable wet-bulb levels. There is an upper-limit based on thermodynamics. https://kevinhesterdotlive.files.wordpress.com/2016/05/heat-...
Yes, you must remain indoors in non-evaporative air-conditioning, dehumidification or near sources of cool water, or you die.
Power outages? People can die.