When planners proposed the opening date of the 1964 Tokyo Olympics, they pored over historical weather data in search of the day with the lowest statistical likelihood of rain. It turned out to be Oct. 10. Happily that day, a Saturday, was fine. As the national teams marched onto the track of Yoyogi Stadium, the maximum temperature was a comfortable 20.9 degrees Celsius. And over the seven days that followed, the average temperature was 21 degrees.

One does not need to gaze into a crystal ball to know that the opening ceremony of next year's Olympics — Friday, July 24 — is almost certainly going to be considerably hotter and more humid.

To prevent wear and tear on the athletes, volunteer guides and spectators, the start of events such as the women's and men's marathons — to be held on Aug. 2 and 9, respectively — will be scheduled as early as 5 a.m. And even then, concerns are already being voiced that they will be grueling events.