Weather is probably a major factor when you plan your trip to Samosir, but bear in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually June and July, with an average temperature of 24°C, while the coldest months are January and February, with an average of 23°C. The rainiest months in Samosir are November, December, October and September, with each month seeing an average of 420 mm of rainfall.