Extremely hot and excessively humid weather. Usually necessitates walking around with one's arms held out from the body (in the manner of a cormorant drying itself after diving for fish) to provide some small measure of armpit ventilation. No matter how expensive your underarm deodorant is, expect it to give up the ghost roughly half an hour after application.
"Whew! Forty-two Celsius and ninety-five percent humidity... Yup. that's definitely cormorant weather. Welcome to Darwin!"