Weather will likely play an important role when you plan your trip to Bukit Lawang, and keep 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 temp of 80°F, while the coldest months are January and February with an average of 78°F. The rainiest months in Bukit Lawang are November, December, October, and September, with each month seeing an average of 15 inches of rainfall.