湿度 as "humidity" in general

Question

I'm using materials I found on the Internet to learn grammar points. This source includes examples, which is really nice, but I reckon there are many mistakes - mostly typos, but sometimes worse. What worries me the most is whether or not these sentences 1. are actually grammatically correct, and 2. sound natural for native speakers.

I came across the following sentence:

私が疲れるのは、暑さというよりはむしろ湿度のせいだ。

The translation is (re-translated from French, sorry if the English is not perfect either):

Rather than heat, it's more because of humidity that I'm tired.

The reason why I'm asking this question is the use of 湿度 to mean "humidity". To my understanding, it means "the humidity level", as in "90%", just like 温度 would be used to refer to the actual value in degrees. Is it acceptable to use it in this case, where I understand "humidity" as a more general concept than just a figure? Wouldn't 湿気 be more suited?

Also, the grammar point this example accompanies is "というより". Is it natural for a native speaker to use this construct in this context?

And more generally speaking, does this sentence sound natural? For instance, could one say "疲れているのは" to insist on the fact that they're tired at this particulat time?

Source, in French but for completeness: http://jlptgo.com/grammaire/187-japonais-to-iu-yori

Answer 1

私が疲れるのは、暑さというよりはむしろ湿度のせいだ。

I think it's valid sentence. The author feels tired because of humidity regularly rather than being directly annoyed by high moisture of the surrounding air. So,「湿度」fits to the sentence better than「湿気」.

「湿気が多い」could be the reason of your tiredness though, I think it often implies how annoying your surrounding is such as clothes not getting dry, your foods getting easily mold, mites get breeding and so on.

Probably the author wants to indicate how humid summer in Japan is comparing to that of other countries.

　Also, the grammar point this example accompanies is "というより". Is it natural for a native speaker to use this construct in this context?

Yes, I think it's valid and you can omit「むしろ」from the sentence and it holds the same meaning.

And more generally speaking, does this sentence sound natural? For instance, could one say "疲れているのは" to insist on the fact that they're tired at this particular time?

I think so. It's valid to switch to "疲れているのは" for that particular moment.