My source was Wikipedia, I know, but I couldn't really find another source that was good, if you find a better one just link it to me in the comments and I will update the quiz. I was suprised by Malaysia and Singapore as well.
Singapore is on average very hot but the ocean mediates the climate and so you don't see the same temperature extremes as you see in more continental climates. I'm guessing the same is true for Malaysia. On the US-states version of this quiz, the state with the lowest record high temperature is Hawaii, right below Alaska.
Yeah that's what I was thinking while making the quiz also, I was thinking it would just be like northern European countries but I was really surprised at some.