>>64204661
Yes, high humidity is worse. Familiarize yourself with the concept of a wet-bulb temperature.
Sweating keeps body temps down because of evaporative cooling. Humidity of the air plays a huge role in how this works.
Look up a wet-bulb temp chart.
A mid 80 F temp with mid 80's relative humidity is more dangerous than a dry heat of 110 degrees.
Desert heats are generally more tolerable assuming a person had enough drinking water to keep up with their sweat loss.