Comparing that to the aircon in the buses... Getting soaking wet while hiking in MacRitchie, no problem. Riding the bus home and fearing to catch a cold because it feels like European winter with shorts and a wet shirt.. not fun.
I used to hike/run MacRitchie every weekend or other weekend, the full 16km. The trick is to bring a spare T-shirt in a plastic freezer bag (press before sealing to remove all the air). When you get back to the Mushroom Cafe, remove your soaked T-shirt and put on the dry one. I think it ranks with the first coffee of the morning in life's greatest small pleasures.