Even though Portuguese summer aren’t usually all that humid (our Mediterranean climate usually brings sunny weather and dry air), in the past few years I’ve noticed some summer days where the relative humidity is quite high while the temperatures are not as high as they normally would be (hovering between 25-30ºC max when they usually go upwards from 35ºC). When that humidity is not accompanied by clouds and light rain, the result is virtually the same: you sweat a lot when you’re outside and you’re always trying to find some shade (unless you’re at the beach or by some riverside).
All of this to say that the word for humidity/moisture isn’t the same in Portugal and in Brazil: over here we write [a] humidade, across the sea Brazilians write it without the h, [a] umidade. In case you missed it, I explain exactly why EP choose to keep the h in words from the family of húmido/a (moist, humid) on my Grammar Tips article about the letter h.