"There's a high moving in just north of us on Sunday ... so it should probably be a fairly okay day.
"There might be some cloudy periods though."
Sunday is set for a high of 19C and a low of 11C with showers and a little wind, according to MetService.
Mr Duncan said there might be a few showers around for the bronze final between Australia and Wales on Friday night.
MetService said it would be about 13C during game time at Eden Park.
Mr Duncan said the forecast for this year's Labour Weekend was good with the northern parts of both islands faring especially well.
"Nelson and Marlborough look good, so does Bay of Plenty, Eastern Coromandel, Auckland and even Northland."
"It won't be perfect, but you'll get the sunniest and warmest weather in those places."
Mr Duncan said Auckland had traditionally experienced quite a showery Labour Weekend, but would be in for more sun than usual this year.
"Even though there are showers in the forecast, the drier weather definitely outweighs the wetter stuff."
Motorists looking to head away for the long weekend were advised to take extra care on the roads.