"Hopefully the front arrives earlier, then conditions will improve considerably by the end of the show."
Further south, it was also looking like rain on the first day of Very Welly Christmas in the capital.
"Sunday is looking the better day weather-wise, with just the chance of an odd shower and a brief southerly," said Coutts.
MetService said the weather should improve in most places on Sunday, especially in the north and east of the country. A few showers will pepper the west and south.
It was expected to be windy, especially about Foveaux Strait and central regions.
If bad weather cancels Coca-Cola Christmas in the Park tomorrow it would be postponed until Sunday.
Saturday
Auckland Rain 23C
Wellington Rain Gales 19C
Christchurch Rain 25C
Dunedin Showers, some heavy 23C