Weather is probably a major factor when you plan your trip to Krakatau, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually October and September with an average temp of 82°F, while the coldest months are August and July with an average of 81°F. The rainiest months in Krakatau are January, December, February, and March, with each month seeing an average of 12 inches of rainfall.