"We have informed the United Nations about the (approximate) date of re-entry, and we will increase efforts to coordinate with them transparently during the process", Foreign Ministry's spokesman Lu Kang said at a press conference. Smaller pieces will land on Earth, we just don't know where.
The 9.4-ton, school bus-size space lab is tumbling, making it almost impossible for analysts to determine the effects atmospheric drag has on its trajectory.
The show will likely be spectacular, and people can track its re-entry by pulling data from two websites.
The redoubtable cataloguer of space activity, Jonathan McDowell from the Harvard-Smithsonian Center for Astrophysics, reckons Tiangong is only the 50th most massive object to come back uncontrolled. It did, however, offer assurances that it is "unlikely to cause any damage".
If it had, the space station would have been dragged down closer to the original estimated entry time.
Boffins are unclear about where parts from the space station will eventually land and many experts even believe most of the debris will burn up during the re-entry.
The agency said in a blog post Sunday that this was its "final estimate" because it is "at the limit of what we can forecast".
The chances are 1 million times greater of winning the Powerball jackpot than by being hit.
The module - which was used to practice complicated manual and automatic docking techniques - was originally meant to be used for just two years, but ended up serving considerably longer.
Pupils fly paper planes during a live broadcast of a lecture given by Shenzhou-10 spacecraft astronauts (on screen from L to R, Zhang Xiaoguang, Wang Yaping and Nie Haisheng) on the Tiangong-1 space module, at a primary school in Hengyang, Hunan province June 20, 2013. It was built to serve as base on which a larger, multi-module space station was to be constructed in the 2020s.
The last space lab to fall to Earth was Russia's 135-ton Mir space lab in 2001.
Tiangong-1 had been slated for a controlled re-entry but ceased functioning in March 2016. In fact, the chances of being hit by one larger than 200 grams is about one-700 millionth.
China's Tiangong-1 spacecraft will re-enter the Earth's atmosphere at some point tomorrow, China's space agency said in a statement.
A Chinese spaceflight engineer, however, denied earlier this year that it was out of control.
The announcement was the first time Chinese authorities had admitted the spacecraft was out of control on its return to Earth.
China has its own space tracking network and could publicly announce the reentry itself, of course, probably via its official news agency, Xinhua.