There may be times in certain countries which are better to visit than other times. This may be because this country may have strong snowy winters or burning hot summers. These extreme climates make it difficult to want to vacation there. However, Singapore does not have that issue. Therefore, the best time to visit Singapore would be any time.
The climate in Singapore is great at a balmy eighty degrees Fahrenheit almost year-round. However, if you are wanting to visit Singapore during times when they are celebrating something special or learn more about their culture, then there may be better times to visit than others. For instance, Chinese New Year which is sometimes celebrated in Singapore is in the month of February.