LUNCHTIME UPDATE: Traffic crawl continues with 12km queue northbound and delays of at least 40 minutes expected through Kempsey.
But southbound lanes remain unaffected.
Motorists are urged to exercise caution on the Pacific Highway and expect some serious delays and heavy congestion.
The New England Highway may be an option to bypass the traffic.
Roads have been unusually busy this weekend, with traffic traditionally more congested on the day of Christmas Eve, says the Traffic Management Centre of NSW.
About 1.30pm yesterday there was a delay of two hours through Kempsey with a traffic queue some 25kms long.
Congestion has started at Buladelah, and is expected to intensify throughout the day.
For those Sydney bound - there has been a single car accident and temporary westbound lane closure in Annandale, on Parramatta Rd at Johnston Street.
Lane 1 is closed but motorists can use Northumberland Avenue as an alternative route.