You should have two options for travel between Picton and Christchurch:
Note: You can usually access Kaikōura via the Inland Road (Route 70) if SH1 is closed. Check real-time information. (external link)
WARNING: Google Maps sometimes displays State Highway 1 status incorrectly. Do not always rely on your GPS for accurate journey information.
For advice on how to plan ahead and stay safe during winter, go to www.nzta.govt.nz/winterjourneys