Weather will likely play an important role when you plan your trip to Tena, and keep in mind that cheaper options are usually available when the weather isn't as good. The hottest months are usually September and October with an average temp of 66°F, while the coldest months are July and August with an average of 64°F. The rainiest months in Tena are April, May, June, and March, with each month seeing an average of 17 inches of rainfall.