The weather forecast for the upcoming Tokyo 2020 Olympic Games has begun to move into a higher-confidence range with just 9 days to go until the opening ceremonies, and so far, it appears that the worst concerns over heat will be avoided.
The forecast currently calls for “scattered thunderstorms” on the day of the opening ceremonies, July 23, according to both Weather Underground and Interia Weather, with more storms continuing through the weekend.
That rain, however, should help keep the temperatures down Both sites also forecast slightly-below-average outdoor temperatures for the duration of the games.
That’s an improved forecast from the original timing of the Games in 2020, which saw the country mired in a heat wave with record temperatures across the country rising to 41.1 degrees Celsius (106 degrees Fahrenheit) in parts of the country in August.
Outdoor events scheduled for the first week of competition at the Olympics that could be impacted by heavy rain and thunderstorms include road cycling, canoeing, equestrian, field hockey, soccer, rowing, and beach volleyball.
The two outdoor events on the aquatics schedule for the Tokyo 2020 Games, the women’s and men’s 10km races, will be held on August 4 and 5, respectively. At present, the forecast calls for a high of 86F (30C) on August 4 and a high of 88F (31.1C) on August 5.
Both the men’s and women’s races are scheduled to begin at 6:30AM local time in Odaiba Marine Park in Tokyo. Long range forecasts for that time of the morning project about a 78 degree Fahrenheit (25.5 Celsius) air temperature at race start time.
FINA’s currently-mandated acceptable water temperature range of 16-31 Celsius, or 60.8-87.8 Fahrenheit. A survey of water temperatures done by Olympic organizers in 2019 showed that from August 7 to 18, water temperatures did not exceed 31 Celcius, with a maximum high of 30.8 Celcius.
Another factor that could impact water temperatures is the amount of rainfall received – it is currently forecast to rain, albeit not heavily, on both days of the open water event. Studies show that rainfall can reduce surface water temperatures in saltwater bodies by as many as 6 or 7 degrees, depending on the size of the drops.