My intuition tells me that this guide risks missing a crucial nuance by focusing only on raw humidity.
The impact of humidity on thermal comfort is often presented as a universal truth, but it is mostly conditional.
Take Singapore as an example: it is always very humid, but hotels and buildings are all air-conditioned and dehumidified; the feeling is very different from what one would imagine just by looking at weather figures.
The real question for the traveler is not just the humidity level, but rather the local solutions to cope with it.