Weather will likely play an important role when you plan your trip to New Amsterdam, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and October, with an average temperature of 28°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in New Amsterdam are May, June, July and December, with each month seeing an average of 440 mm of rainfall.