"These bands of rain are not moving fast so will stick around for much of the day possibly bringing large accumulations," the Facebook post said.
"If you are heading away for the long weekend be aware there may be some surface flooding around the region."
NZTA is including the hashtag #LionsNZ2017 in their traffic update tweets.
The AA is warning motorists they should leave before lunchtime to avoid getting stuck in the worst of the traffic.
It warned traffic in Auckland would likely be locked up until 8.30pm. Those driving on Saturday should avoid the 11am-1pm window and when coming home on Monday drivers should try to remain outside the 2pm-6pm window.
