Athletes compete during the Rio 2016 Paralympic Games men's marathon T54 event in Rio de Janeiro, Brazil, September 18, 2016.
The Paralympic 2020 marathons are staying in Tokyo, unlike the marathons for the Olympics, which have been moved north to the cooler city of Sapporo.
International Paralympic Committee (IPC) President Andrew Parsons confirmed the move on Thursday as Tokyo 2020 organizers wrapped up planning meetings with the IPC.
The Paralympics will open on August 25, several weeks after the Olympics close on August 9. And Parsons said data shows the heat and humidity should not be a problem.
He emphasized the athletes did not want to leave Tokyo.
"When we spoke to athletes likely to compete in the Tokyo 2020 marathon events, the overwhelming response was that they want to remain in Tokyo," he said.
"With many marathon athletes also competing in track events during the games, a move would be logistically difficult for them to accommodate."
Parsons added: "The health and well-being of our athletes is a top priority for us at all times. And before taking a final decision to keep the Paralympic marathon events in Tokyo, it was vital for us to analyze all the relevant data and speak to the athletes themselves."
Athletes compete during the Rio 2016 Paralympic Games men's marathon T54 event in Rio de Janeiro, Brazil, September 18, 2016.
The Paralympic marathons take place on September 6, the last day for the Paralympics. Parsons hopes the races can kindle a street party to celebrate Tokyo's seven years of preparing both the Olympics and Paralympics.
"With the Paralympic marathon events now confirmed, we want to work with Tokyo 2020 and Tokyo Metropolitan Government to ensure the final Sunday of the Paralympics is a huge celebration and a street party which the whole city can enjoy."
Five marathons take place on the final day with the first starting at 6:30 a.m. local time.
The triathlons were also moved up an hour from 7:30 a.m. to 6:30 a.m. on August 29-30.
The decision to keep the marathons in the Japanese capital should please Tokyo Governor Yuriko Koike, who bitterly opposed moving the Olympic marathons but was overruled by the International Olympic Committee (IOC).
Parsons announced earlier there has been a record of 3.1 million ticket requests for the Paralympics – more than the 2.3 tickets available. Now he's looking for something else that's unprecedented – a sellout before the games begin.
The Paralympics are following the course of the Tokyo 2020 where ticket demand far exceeds supply – perhaps by a factor of 10 or more.
"There is real opportunity here for Tokyo to become the first Paralympics in history to sell out ahead of the opening ceremony," Parsons said.