Climate & when to go
The best time to visit American Samoa is during the dry season from May to October. A less comfortable time to arrive is during the region's wet season between November and April. That said, most rainfall occurs at night and the main discomfort (excepting the odd cyclone) is caused by higher levels of humidity. The exception is the harbour area of Tutuila, where the famous Rainmaker Mountain ensures that the surrounding area receives over 5000mm of precipitation annually.
If you intend visiting the islands around December-January, remember that this is the peak holiday period for Samoan expats living in the USA, Australia and New Zealand (NZ). Book flights well in advance.