"It's the spring rollercoaster ride. We were up at the top of it in the weekend with the nice weather and now we're holding onto the edge of the chair. But give it a few days and things will settle again."
Auckland was likely be hit by a band of rain today, and the eastern side of the North Island would be pummelled by more downpours tomorrow, he said. The warm, unstable air over the central and northern parts of the North Island meant thunderstorms were also possible.
A westerly wind is expected to gradually get rid of the stormy weather on Thursday, and the weather system is expected to have little energy left by the weekend, when Auckland hosts the two knockout matches.
Mr Corbett said: "There still might be a shower risk for Saturday evening in Auckland, but it should be pleasant, around 16C or 17C.
"But if this low eases by a bit more quickly, we could be looking at a drier spell, settled with just some westerlies. It is an improving picture compared to what we'll be seeing [today] and Wednesday."
MetService has placed heavy rain watches for all areas from Taranaki to Gisborne northwards, and warned of potential gale-force winds around northern coastlines today.
Counting down
Saturday
Wales v France
Eden Park, Auckland, 9pm. Fine spells, westerly breeze, with a chance of a shower. 15C.
Sunday
Australia v New Zealand
Eden Park, Auckland, 9pm. Dry, settled conditions with small risk of a shower. 16C.