Lydia - Singapore is on equator - we have all the year summer only with constantly 30C+ & more then 90% humidity. It is like a huge hothouse and it is unbearable hot in open areas specially in sunny days.
Konstantin
I also wouldn't recommend you to do this Lydia ... and the reason is that topless tour means in Singapore a tour in a bus with open area on its top.
AND I WOULD RECOMMEND NOBODY TO TAKE A SIT IN OPEN AREA IN SINGAPORE !
Konstantin.