Holidaymakers are heading back to Auckland in droves, causing traffic jams between Wellsford and Puhoi.
Waka Kotahi New Zealand Transport Agency is warning motorists to expect delays between Puhoi and Wellsford in both directions with southbound traffic expected to be heavy until about 6pm.
Images show northbound traffic almost at a standstill heading into the Johnstones Hill tunnel.
"Be prepared for heavy traffic southbound on #SH1 between Puhoi and Wellsford from 8:00am - 6:30pm today as motorists return to Auckland following the holiday period," the organisation's Twitter account warned this morning.
"Traffic is busy southbound today on #SH1 between Wellsford and Puhoi, with delays also northbound through Puhoi. Allow additional time for your journey if you're on SH1 north of Auckland today," it said this afternoon.
About 2pm motorists warned traffic was backed up past Dome Valley heading south and was very slow coming into Warkworth.
Google maps estimates a 20-minute delay heading south due to heavy traffic between Goatley Rd and Warkworth town centre.
It also showed a heavy patch through Puhoi.
Earlier a breakdown on Auckland's harbour bridge blocked a southbound lane, with two others closed for resurfacing, causing major delays.
Those heading back into Auckland from the north were also advised to expect major delays between about 9am and 7pm tomorrow and 11am and 7pm on Sunday.
The Southern motorway heading north is currently free-flowing according to both Waka Kotahi and Google maps.