Planning for the weather is an important factor for making your trip to Nieuw Amsterdam a success, especially when you're splurging. The hottest months are usually September and October, with an average temperature of 27°C, while the coldest months are January and February, with an average of 26°C. The rainiest months in Nieuw Amsterdam are May, June, July and April, with each month seeing an average of 296 mm of rainfall.