Weather is probably a major factor when you plan your trip to Jember, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually October and November with an average temp of 78°F, while the coldest months are August and July with an average of 76°F. The rainiest months in Jember are January, February, December, and March, with each month seeing an average of 17 inches of rainfall.