Drivers who are caught risking their safety and that of others this holiday weekend will not be let off with a warning, police say.

Road policing director superintendent Steve Greally said he did not want families and communities having to face the tragic consequences of a bad decision on the road.

On Tuesday, a crash in Waikato left five people dead.

Greally said police would be "out in big numbers" this King's Birthday weekend, making sure they deterred people from making bad decisions.

"Where they don't, we will hold them to account," he said.

Drivers caught risking their safety and that of others could expect to be fined, disqualified or even jailed, he added.

"Don't expect a warning - if you're pulled over for offending on our roads, it's really important to understand we want people to get home safely, simple as that. It doesn't get more serious than losing your life."

Last year, four people died on the roads over King's Birthday weekend.

Saturday also marks the official start of winter. Greally said New Zealand's climate was very unpredictable and changeable, particularly on a long drive, and drivers should adjust their driving style to the conditions.

Waka Kotahi New Zealand Transport Agency said drivers should check both weather and conditions at the time of year.