Rangi Tapu, 25, of Auckland is assumed drowned after failing to return from diving off Cable Bay on January 8, although his body is yet to be recovered.
Virginia Lee Smith (54) of Rawene drowned after getting caught in a rip while swimming at Takou Bay, north of the Bay of Islands, on January 17.
Provisional data shows 12 people drowned in Northland in 2014, a slight decrease from 2013 when 14 drowned.
The number of drownings on unpatrolled beaches so far in 2015 further reinforced the need to always choose a patrolled beach and swim between the flags, Mr Dalton said.
"People are continuing to overestimate their ability and underestimate the conditions and this is a deadly combination," he said. With another 10 weeks left to go of the official surf life saving patrol season and another long weekend just around the corner, Surf Life Saving New Zealand is calling for vigilance, Mr Dalton said.
If people were going to continue to choose to swim at an unpatrolled beach, they needed to take more care and understand what risks they might be getting themselves, or their children, into and take practical steps to avoid them, Mr Dalton said. "They should only go in the water once they know for sure it is a safe place to swim," he said. "It may look beautiful, but be deadly."
Water Safety New Zealand CEO Matt Claridge said the good weather meant more people were enjoying the outdoors.
"But this also means people need to take real care and consider how they're going to keep themselves and their whanau safe around water."
Surf Lifesaving Ruakaka patrol captain Craig Platt said there had been no rescues at the weekend despite the water being "really, really" warm.
"This weekend has been really quiet for us," he said.
Surf Lifesaving Mangawhai patrol captain Finn Tischik said the beach was getting quieter but numbers were expected to be higher over Waitangi Day weekend.
"We've had a couple of little rescues but nothing major," he said. Those rescues were mainly preventive actions to ensure swimmers were not getting into real trouble, he said.