The Wellington City Council expects up to 70,000 people a night in the downtown area during the quarter-final phase of the Rugby World Cup this weekend.
The council says about a third of those are visitors to the capital.
Wales beat Ireland 22-10 in a quarter-final match at Wellington Regional Stadium on Saturday, while South Africa line-up against Australia on Sunday.
Wellington Airport expected 18,000 international passengers and 12,000 domestic passengers on Friday - one of its busiest days to date.
Positively Wellington Tourism chief executive David Perks said staff at the visitor centre in Civic Square have been run off their feet and accommodation is booked solid throughout the region.
The council expects entertainment district Courtenay Place to reach capacity at 25,000 people and the waterfront fan zone to fill up with about 3000 rugby fans.
More than 40,000 people are expected to use the city's trains this weekend - five times the usual number - and thousands of people will also use the city's bus network.
KiwiRail is putting on at least a dozen services a day and a spokesperson says it is more than capable of dealing with so many passengers.
Anyone driving to venues is advised to allow plenty of time for their journeys.
Wellington City Council operations manager Mike Mendonca says the capital has a proven history of running big events, and no problems are expected.
Meanwhile, Wellington Airport's acting chief executive believes Monday may be even busier.
John Howarth says the airport has trialled additional systems in recent weeks, so staff are calm and confident. Twenty-five Rugby World Cup volunteers will also be at the airport to help passengers.