From Tuesday, traffic flow will revert to northbound only until further notice.
For safety reasons, the road will remain closed overnight, from 8pm to 8am, and conditions would be re-assessed each morning, as safety is the top priority, Waka Kotahi says.
Contractors and geotechnical engineers will be on site throughout the weekend monitoring for any additional slips or ground movement on or near the road, and the road may close at short notice should conditions become unsafe.
Temporary speed restrictions will be in place.
Waka Kotahi urges motorists to use caution and drive to the conditions.
When SH1 is closed, light vehicles will need to continue to use the local detour via Mangawhai, while heavy vehicles will need to continue to use SH12 and SH14 state highway.