Weather is probably a major factor when you plan your trip to Halmahera, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually October and May, with an average temperature of 28°C, while the coldest months are July and August, with an average of 27°C. The rainiest months in Halmahera are May, June, January and December, with each month seeing an average of 288 mm of rainfall.