My intuition tells me that a travel guide that categorizes a place as “challenging” due to humidity oversimplifies things; it seems like a trick to sell a book rather than a deep analysis. Thermal comfort is such a more complex concept than just humidity, and this idea smells of incomplete information. For example, in Singapore, it’s hot and humid all year round, but people live very well thanks to air conditioning infrastructure everywhere, which makes the traveler’s experience quite different from what one might imagine just looking at humidity figures.