The key message from the agency to help motorists avoid traffic headaches was "plan ahead".
A spokesman said traffic was likely to be heavy during the middle of the day tomorrow, heading in any direction on the motorway.
"I think the day before Christmas is usually worst, but this year it might be slightly different because people are finishing up work a couple of days before," he said.
"They've got a couple of days to get away so it might be more spread out."
Not surprisingly sections of upper North Island highways were expected to be clogged for up to eight hours over the Christmas and New Year period. The beginning of the gridlock was anticipated to kick in from around midday today.
Some of the worst affected areas were heading south on Auckland's Southern Motorway from Takanini and heading north between Puhoi and Wellsford.
Commuter chaos was also expected on State Highway 1 near Whangarei as the holiday period kicked into action.
Further down the island, NZTA had also predicted congestion heading out of Wellington to the Kapiti Coast as well as over the Rimutakas between Wellington and Featherstone.
In the South Island, State Highway 6 (Nelson-Blenheim, and at Murchison) and nearby to the east State Highway 63 (St Arnaud) are the roads to avoid if you can between December 27 and the first days of the New Year.
Meanwhile police are urging motorists to take care on the roads, to make sure no one is missing their loved ones at the Christmas dinner table.
"The speed you're travelling at has a huge impact in the outcome of a crash and is the biggest determinant in whether anyone is killed, injured, or walks away unharmed," he said.
"This is why we also do things like have a lower speed threshold over the holidays on our safe speed cameras. We want people to slow down while they're travelling to see loved ones over the holidays."
The pleads for caution follow a horror few days on New Zealand roads this week.
Four people died in a 24-hour period over Tuesday and Wednesday.
On Thursday night the official road toll for 2017 stood at 366. On the same date last year, 310 people had died on our roads.
