The Southern Air Temple was the boyhood home of Avatar Aang, and his fatherlike mentor, Monk Gyatso. It was also home to Avatar Roku when he needed a place to master the art of airbending.
The temple was raided during Fire LordSozin's genocide on the Air Nomads and instigated the Hundred Year War. The sole known survivor of the massacre was the very person the Fire Nation sought to kill in its quest for supremacy: the twelve-year-old airbender and Avatar, Aang, who had ran away from the Southern Air Temple shortly before the War began, and became trapped in suspended animation. He has since been revived and begun a quest to restore balance and peace to the warring nations.
One hundred years later, the temple was revisited by Aang, with his friends Katara and Sokka. There, he met one of the last winged lemurs in existence, which he named Momo. While there, Aang discovered the fate of the Air Temple and its people, including Gyatso, causing him to realize that all the Air Nomads were wiped out and that he, Appa and Momo were all that remained.
The temple is large and peaceful, has an airball arena, and is also where the "air scooter" was first invented by Aang. Additionally, the massive facility features a sanctuary in which reside numerous statues of past Avatars. The temple itself primarily served as a training ground for airbender students. Once inhabited by flying bison and winged lemurs in the days of the monks, it was left empty and lifeless after the Fire Nation murdered its populace. As a result of being built for and by the monks, several of the temples' doors and mechanisms are operable only through means of airbending. A statue of Monk Gyatso stands at the entrance to the temple. Unlike the other three temples, the Southern Temple boasts blue, elaborately decorated spires rather than green, plainly decorated ones.
Furthermore, The Lost Scrolls: Air, page 212 of The Lost Scrolls Collection, states that Momo originated from the Jongmu Air Temple. Considering the fact that the information in The Lost Scrolls series is taken from episode screenplays, the Southern Air Temple was still titled "Jongmu" up to that stage of production. Page 232 uses "Jongmu Temple" (instead of "Jongmu Air Temple") in place of "Southern Air Temple", as does the final page of The Lost Scrolls: Air.