At this time next year, the world's greatest collection of athletes will gather in Tokyo to compete in the 2020 Summer Olympics. If the weather is anything like it has been in recent summers, the heat may prove to be the athletes' fiercest competitor.

A year out, it is impossible to forecast what the exact weather may be, but historical trends can paint a picture for what fans and athletes can expect during a typical Tokyo summer from July 24 to Aug. 9, the dates of next year's Games.

'Typically highs during the period are in the middle 80s (28-29 C) and lows are typically in the low 70s (around 23 C),' AccuWeather Senior Meteorologist Jason Nicholls said. 'But it is not uncommon for highs to reach the upper 80s and low to mid-90s during that time of year. So heat could be a factor.'

The warm conditions could make events more difficult for athletes participating in long-distance events, such as the marathon run or triathlon. At the request of health officials, event organizers agreed in April to move up the start time for the marathon, now at 6 a.m., to avoid running during peak day heat. The women are scheduled to race on Aug. 2 and the men on Aug. 9.

Tokyo olympics 2020
Tokyo olympics 2020

A study conducted by French researchers in 2012 analyzed thousands of marathon performances from 2001 to 2010. In their findings, they concluded that air temperature is the most impactful factor on elite runners' finishing times. According to the results, the ideal temperature for elite women finishers was 49.82 F (9.9 C) and 42.8 F (6 C) for elite men finishers. The study also found that for these elites, speed loss percentages and withdrawal rates sharply climbed with each increase of temperature.

At 85 F (29.44 C), the study found that women's performances saw a 13.47 percent speed loss, while men saw a 6 percent speed loss.

'Air temperature is the most importance factor influencing marathon running performance for runners of all levels,' the study said. 'It greatly influences the entire distribution of runners' performances as well as the percentage of withdrawals... any increase or decrease from the optimal temperature range will result in running speed decrease.'

Nicholls echoed a similar sentiment about the temperature's impact on runners and added that another heat wave, like the city saw in 2018, could play an important role as well.

Tokyo one year to go
Tokyo one year to go

Throughout most of July 2018, many regions of Japan experienced a record-breaking heat wave that killed at least 138 people and hospitalized over 70,000 for heatstroke.

'Heat waves have been commonplace in recent summers and a stretch with highs in the 90s could test endurance, especially for marathon runners,' Nicholls said. 'Rainfall and severe weather could also be a concern at times.'

 
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Along with the deadly heat wave of last summer, 2018 also saw a record number of tropical cyclones make landfall in Japan, according to Nicholls. He added that tropical systems can be a wildcard for southern Japan.

Regarding precipitation, Nicholls said that the 2019 summer has been wetter than normal, opposite of the previous two years. Although, he added, precipitation trends are more jumbled than temperature trends.

'The overall trend seems to be for warmer-than-normal weather during the summer, so heat may be a factor in 2020 given trends and the look of some weather patterns,' Nicholls said.

Tokyo heat wave olympics
Tokyo heat wave olympics

While this isn't the first time the city has hosted the Olympic Games, the last time Tokyo served as host was in 1964, when the event was held in October.

Many have suggested that organizers shift the date to the fall, but those chances are extremely slim because of the already established event schedules, tickets sold and TV broadcasting rights.

To counteract the weather, organizers have begun to establish guidelines, policies and installations to help spectators and fans deal with the heat. In the Olympic Stadium, beams were installed that are designed to circulate air and keep spectators cool, according to Japan Sports Council official Keiji Kato.

tokyo summer olympics
A boy walks through the Olympics rings while posing for photos as New National Stadium is seen in the background Monday, June 17, 2019, in Tokyo. (AP Photo/Jae C. Hong)
Jae C. Hong/AP

Organizers also hinted that spectators may be allowed to bring in their own bottled drinks to venues for the Games. Games delivery officer Hidemasa Nakamura told The Japan Times that first-aid staffers will be consistently available to treat heat-related illnesses and provide transportation, if needed, to medical facilities.

With a year to go until the Games, many other tweaks can be expected from organizers to prepare for what might go down as the hottest Olympics ever. Nakamura said that along with consulting athletes and the governing sports bodies, some heat safety procedures will be tested at upcoming summer athletic events.

'We alone cannot come up with the best ideas,' Nakamura said. 'That's why we've invited athletes and other groups, so we can get all kinds of comments about the best ways to fight the heat. This is all aimed at making spectators feel as comfortable as possible, given they have come to see events in a very hot and humid environment.'

Download the free AccuWeather app for more details on temperature trends in your community. Keep checking back for updates on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.