Uncertainty only certainty for kick-off conditions

Photo / Dean Purcell

When the Rugby World Cup final kicks off on in Auckland in four months' time, there is about a 50 per cent chance the game will be dogged by rain.

The weather cannot be accurately predicted months ahead, but past climate records give an indication of what rugby fans and the projected 85,000 visitors can expect in September and October.

The only assured forecast of World Cup weather is that it will be changeable. Last October was spectacularly sunny with numerous temperature records broken. October 2009, however, was the coldest October in more than 64 years.

The opening rounds of the tournament are likely to be played out in typically erratic spring conditions - intermittent rain and blue skies, with plenty of wind.

But Niwa climate scientist Georgina Griffiths said weather usually became more settled in October, when the knockout rounds of the competition will be played.

"Typically as we move from September into October, things tend to calm down a bit. More anticyclones will start to dominate and for longer, and we will get more settled, light wind, and mostly sunny periods that last two to three days."

On average Auckland has about 17 days of rain in September and 16 rainy days in October. That rainfall, however, can be as little as 0.1mm and pass quickly.

As for temperatures, Auckland is usually a chilly 9.5C in the morning in September, warming to about 16.1C in the afternoon. October days start at 11.2C and warm to about 17.6C.

Ms Griffiths said visitors from continental climates would notice two things about Auckland on arriving.

"The temperature doesn't really change a lot over the course of a day relative to what they are used to.

"And also, we get a lot of showers moving through quite quickly - brief showers of rain, followed by bright blue sunshine."

An unscientific look at the day of the final also shows anything could be expected in Auckland.

In the past five years, October 23 has seen temperatures between 9.2C and 19.2C, wind from every direction, heavy rain and perfect blue skies.

The teams' goalkickers should also be aware that October is the windiest time of the year in Auckland - they will almost certainly be competing with strong westerlies and south-westerlies at Eden Park.

Rugby sides wanting the breeze at their backs in the second half should hope to play towards the old terraces in the first half.

While Dunedin has fewer rainy days than the North Island, it is also colder - between 5.7C and 14.8C during the tournament. Come September, however, the city's rugby followers won't even have to pack a raincoat. The new Forsyth Barr Stadium will have the only antidote to spring weather in New Zealand: a roof.

World cup weather

September

Auckland: 17 days of rain (on average), 8.9C - 16.2C
Wellington: 15 days of rain, 7.7C - 15C
Dunedin: 15 days of rain, 5.7C - 12.9C

October

Auckland: 16 days of rain, 10.5C - 17.8C
Wellington: 15 days of rain, 9C - 15C
Dunedin: 16 days of rain, 7.2C - 14.8C
Auckland on World Cup Final day:
Oct 23, 2010: light westerly, dry, 9.2C - 17.2C
Oct 23, 2009: fresh southwest winds, dry, 11.7C - 16.1C
Oct 23, 2008: moderate northerly, rain, 13.1C - 19.1C