They advised that motorists should use alternative routes and expect delays.
The delays north of Auckland were expected to be at their worst yesterday, according to transport agency Waka Kotahi.
Also featured on the list were areas such as the Coromandel, specifically State Highway 25 northbound traffic near Tairua, which is expected to be extremely congested on Christmas Day afternoon, early Boxing Day afternoon, and on December 27, according to Waka Kotahi.
Beginning on January 1, traffic around Tairua will be congested in both directions. Drivers should anticipate heavy traffic the whole first week of the new year.
Eastbound traffic on SH2 between Pokeno and Maramarua is anticipated to be heavy through Boxing Day and again around New Year. January 8 is a day to keep an eye on since high traffic volumes are expected in the early afternoon.
Kapiti Coast was showing up as likely to be significantly congested on Thursday. For most lunchtimes in the next week, the worst spot will be traffic merging onto SH1 at the northern exit of the newly opening expressway at Otaki.
Another significant jam was predicted at Queenstown on Christmas Day and around the New Year.
In Otago, there will be delays at the single-lane Beaumont Bridge on SH8. The good news - not that it helps anyone in the next week or so - is that the delays are due to the nearby construction of a new bridge with two lanes.
After a short break over the Christmas-New Year period, Waka Kotahi will be ramping up resealing of about 10 per cent of the highway network, much of it in Otago and Southland.
“In many areas, the wet early summer means more activity with road crews working nights as well as days, so please take care around these crews and keep alert for traffic management advice,” the agency said.
“If you are driving long distances around the South Island these summer holidays, add an hour to the usual journey time.”
Waka Kotahi said it was an unfortunate coincidence the summer holiday travel peaks coincided with the best time to resurface roads, “the warm temperatures and dry air help[ing] the new seal stick to the road surface”.
Last year, 17 people lost their lives over the official holiday period - one of the worst figures in the past decade.
“Drive to the conditions, allow plenty of time and take regular breaks to stay alert,” the agency said.