These facts make sight seeing a bit of a challenge - unless you adopt a nocturnal strategy. Not only does the temperature drop when the sun goes down, but so does the humidity. Mornings are often a sticky 90% or more, but mid-afternoon typically dips to around 60% (when it isn't raining).
So things get cooler and more comfortable as the day wears on, but what does heat up is Singapore's high tech, nighttime light-scape (...suddenly, afternoon naps make even more sense).
One notable hot spot is surrounding Marina Bay.