"There's a low coming from the east and a trough from the west that will bring showers from Wednesday for most places. Things will clear up a bit for most on Thursday, but unfortunately for Northland there's a small system coming from the north that will bring rain on New Year's Eve and into New Year's Day then into the New Year," Mr Adams said yesterday.
"Northland looks like it's going to be one of the wettest places in the country moving into the New Year."
But Northlanders and holidaymakers have been determined to make the most of the sun while it lasts.
At Waipu Cove, lifeguards were concerned about heat exhaustion, as favourable conditions saw about 200 people flock to the beach yesterday.
"We applied a couple of first aids over the weekend for scratches and grazes. Locals have removed eight tons of algae from the water over the last couple of weeks which has made the beach more enjoyable," Waipu Cove Surf Lifesaving Club captain Dylan McCombe said.
On Sunday, the lifeguards rescued five people who were pulled out to sea.
Among those who made the most of the sizzling temperatures yesterday was Sri Lankan-born Auckland resident Vimashi Perera and her children, daughter Thisini Duwage and son Nuran Duwage. It was their first trip to Waipu Cove and Ms Perera said her family would probably make it an annual summer affair.
"There's a beach ambassador out here which we've never seen at any other beach. We've been to Whangarei before and to Paihia quite a few times before so we wanted to visit some other place," she said.
Mangawhai Heads surf club captain Patria Harris said the beach had been busy all weekend, with more than 500 people most days.
"We've had a few minor rescues but no real problems. Everybody's just enjoying the great weather," she said.
But with the swell expected to rise over the coming days lifeguards were keeping a close watch on Mangawhai Bar which could be dangerous for boaties if they were not careful.
Several hundred people also visited Ocean Beach, at Whangarei Heads, each day without incident.
Ruakaka lifeguards could not be contacted for comment yesterday.