Despite the rain the fans seem to be in a good mood.
"Police are not aware of anyone being breathalised and being ejected or refused entry by security staff for being drunk."
Supporters turned up dressed as everything from teams of blood-soaked medics to superheroes.
And despite the near constant rain, others partied in straw sombreros and beach hats.
Warriors fans Tane and Tracey Ruru, from Whakatane, said traffic on the way in was reasonably light and it took just 30 minutes to drive to the ground from a friend's house in Manukau.
"It was no problem getting here and that put us in a good mood for the day," Tane said.
"It's a great atmosphere and it will be even better if the Warriors win the tournament."
North Shore residents Jim Yule and Jason Jenner bussed it in from Albany.
"It was an easy way to do it and we were at the ground half an hour after leaving," Yule said.
"We thought the rain might spoil it a bit but it's nice and warm, so who cares if it is wet. Nobody seems to be bothered by it."
Bag searches were in place at the stadium entrances but security staff said at this stage no one had been breathalised for being worse for wear because of alcohol.
"But we are expecting to be dealing with people who have had too much to drink by later in the afternoon," a security staffer said.
Fans enjoyed an opening match between the Rabbitohs and the Roosters.
In between matches they queued for pricey food and drink at outlets behind the stands.
Wine cost $10 a pop, as was a Woodstock and Cola.
Beer was $8 and soft drinks were $4.50.
Hungry fans tucked into chicken and chips for $9.50, beef burgers were $9 and hot chips were $4.50.
Helen Lowe, from Papakura, spent about $90 on snacks for herself, a friend and and her two kids.
"It is a bit pricey but not over the top and not as bad as I imagined it would be," she said. "But I will definitely be making some sandwiches to bring to tomorrow's games."
Warriors merchandising staff said business had been brisk with team singlets costing from $50-$80 the most popular items.
The latest Warriors shirts were also proving a hit, costing $180 for adults and $130 for kids.