hot

Its going to get hotter and hotter. So the answer is no, not before, like 5 years ago, but its been raising a degree or two since.

sdds

It does, its not only global warming. Winds don't go through Buenos Aires, they stay there so humidity gets really high specially the last few days before each rain arrives.

Don't worry, the same humidity makes the city quite cold on winter. Personally I think the best season to go to BA is autumn; the weather is very good and its not either too hot nor too cold. On Spring it rains more than on Autumn