Here are some key questions about Typhoon Hagibis, the 19th of the annual typhoon season, and its possible impact on a key weekend of sport.
How dangerous is it?
The Japanese Meteorological Agency (JMA) currently ranks Hagibis as “violent” — its highest possible classification — packing maximum gusts of up to 280 kilometres per hour.
It is predicted to weaken considerably by the time it gets closer to Japan, but it could still potentially be one of most powerful typhoons in recent years, the JMA warned.
On its current course, the eye of the storm is forecast to clip the southeastern corner of Japan near Tokyo and Yokohama, a similar trajectory to Typhoon Faxai which caused massive transport disruption a fortnight before the Rugby World Cup.
However, typhoons often alter course at the last minute and the JMA and World Cup organisers have said it is too early to make firm predictions about the impact.
What games could it affect?
Initially, the path of the storm was expected to take it over Japan’s southwestern island of Kyushu, potentially affecting Ireland v Samoa in Fukuoka and Wales v Uruguay in Kumamoto.
However, a radical change of course made it more likely to hit the Tokyo area on Saturday night. The main match at risk would seem to be England v France in Yokohama at 5:15pm (0815 GMT) on Saturday.
Japan are due to play Scotland also in Yokohama at 7:45pm on Sunday. The storm is forecast to have swirled into the sea by then but the aftermath could still produce bad weather and possible travel chaos.
What plans do organisers have?
Organisers have frequently trumpeted what they call a “robust” contingency plan, with options including postponing a match, moving venues or cancelling it.
In a recent interview with AFP, tournament organiser Alan Gilpin explained the timescale of when they would take a decision on whether to move a match or change the timing of a game.
“From a match perspective, 72 hours out, we want to know really if there are going to be any potential adverse impacts. So that’s the kind of early warning. If it looks like there will be, from that point, we are getting updated information every three hours,” explained Gilpin.
“And then 24 hours out really, we need to know, from a fairly realistic perspective, what is the impact of that tropical storm, typhoon.”
“Where’s that going to strike, what’s the wind speed and what’s the potential impact of that. So we’ll pre-make decisions 24 hours out,” he added.
A decision on cancelling a match would be confirmed “six to eight hours out,” the organiser added.
What happens if match cancelled?
During the pool stages, where the games come thick and fast, there is no possibility of rescheduling a match.
If a game has to be cancelled due to adverse weather, it counts as a 0-0 draw, with both teams getting two points each.
From the knock-out stages, there are reserve days if a match cannot be played.
Who could benefit?
The two matches most at risk are England v France in Pool C and Japan v Scotland in the tightly contested Pool A.
England and France are playing to see who tops the pool. In the case of an abandoned match, this honour would go to England, who currently have 15 points compared to France’s 13.
In Pool A, an abandoned match would be a disaster for Scotland, as it would mean they are unable to qualify. Japan, in contrast, would top the group, setting up a likely repeat of the “Miracle of Brighton” fixture against South Africa in the quarter-finals.
Will it affect the Formula One?
Race organisers are likely to act cautiously after tragedy struck the Japanese Grand Prix of 2014, when Marussia driver Jules Bianchi lost control in heavy rain on the fringes of a typhoon, and remained in a coma until his death the following July.
At its current speed and trajectory, Hagibis is likely to bring its worst weather to the Suzuka track, west of Tokyo, on Saturday.
Organisers may choose to postpone Saturday’s qualifying session until Sunday, the same day as the race, as happened in both 2004 and 2010 as typhoons threatened.