Yes, forecast is saying this typhoon will be big one.

Organizer of Rugby World Cup is looking at alternate locations for this coming Saturday and Sunday games. But with this short notice they are not sure if the can make an arrangement at an alternate location, which includes transporting teams to alternate locations. Getting transportation and lodging for that large number of people in this short notice is not an easy task. The tournament rule state that except for the championship game (the final game) there is an option of cancelling a game and consider it as a tie game. The game which will be affected are:

Saturday 12th:
New Zealand vs. Italy (at Toyota Stadium at Aichi near Nagoya)
England vs. France (at Yokohama International Stadium at Yokohama)

Sunday 13th:
U.S.A. vs. Tonga (at Hanazono Rugby Stadium at Osaka)
Japan vs. Scotland (at Yokohama International Stadium at Yokohama)
Namibia vs. Canada (at Kamaishi Stadium at Iwate)

Following games will not be affected since the location is considered to be out of the typhoon path (at this moment)

Saturday 12th:
Ireland vs. Samoa (at Hakata Forest Stadium at Fukuoka)

Sunday 13th:
Wales vs. Uruguay (at Kumamoto Stadium at Kumamoto)