From wild, to mixed, to dry until after the game has finished, to lashing it down all day, the prognosis appears to be changing by the hour.
Typhoon Tapah is the latest set to hit Japan during its stormy season this weekend but it remains unclear exactly how it will impact on Yokohama, a city which merges into southern Tokyo.
“It’s something we’ve talked about and with the experience and leaders we have we expect them to make good decisions on the pitch,” said Scotland assistant coach Mike Blair at today’s eve of match press conference in Tokyo. “There are things we’ve put in place, conversations we’ve had but in the end we trust the players.”
Scotland scrum-half Greig Laidlaw added: “We’re in the same boat as everybody in that we’re told there is a storm sitting off Japan somewhere but whether it comes in or not we're not sure.
“We've planned that into our game plan and if the weather does come in we can flick to a system that suits that weather.
“That’s been a big part of our preparation. We’ve worked closely with the coaches to make sure we’re all happy and can adapt quickly. If the conditions change it’s certainly not going to be a surprise to us.”
On Friday, Ireland assistant coach Richie Murphy said: “We have just got to adapt to the conditions. World Cups are all about being adaptable.
“Who plays in the team, what the conditions are or what a referee decides, [they] might have a certain way of interpreting a rule so you have to adapt all the time.”
Yokohama has experienced highly erratic all week with ferocious torrents of rain giving way to blue skies and warm sunshine.
“The weather is changing so it's very hard to know and I suppose we will just have to keep an eye on it over the next couple of days,” added Irish skills coach Murphy.
“Two days ago it looked like it was going to be the worst rain shower we’ll have ever seen and now it's saying it will be dry so we will just have to wait and see.”