Games in those cities over the weekend include England v France, Ireland v Samoa and All Blacks v Italy.
"World Rugby has been exploring every possible contingency within a complex and rapidly-evolving environment to ensure a fair opportunity for all matches to be played," the email said.
"Team and pubic safety is the primary consideration and no decision will be made that endangers safety.
"By tomorrow morning, World Rugby is confident that they will have accurate information to make an informed decision regarding impact."
If the England-France game is cancelled it would be the first time in the 32-year history of the tournament.
The match between the two Six Nations rivals is set to take place on Saturday in Yokohama City. If it is abandoned it would mean England will finish top of the group with 17 points and likely play Australia in the quarter-finals. France would end up in second and most likely play Wales who lead Pool D.
Japan's crucial Pool A game against Scotland at the same ground 24 hours later will decide whether the hosts will qualify for the quarter-finals.
The All Blacks' final pool game against Italy is to be played in Toyota City which is on the edge of the predicted path of the typhoon.
The most high-profile weather-affected World Cup match in recent memory was the 1995 semi-final between France and the eventual winners South Africa. A deluge in Durban forced kick-off to be delayed by an hour, though tournament rules state that any cancelled match in the knockout stages will be rescheduled.
For pool stage fixtures, if the match begins but is abandoned before half‑time, two points will also be awarded to both teams although points scored in the match, and bonus points, will still count. The result will stand if a match is abandoned at or after half-time and the same cut-off point applies in knockout matches.
Matches in the potential path:
All Blacks v Italy, Toyota City, Saturday 5.45pm
England v France, Yokohama City, Saturday 9.15pm
Japan v Scotland, Yokohama City, Sunday, 11.45pm
