Bad weather and snow have closed State Highway 63 between Renwick and St Arnaud.
It means people traveling between Blenheim and the West Coast must detour via State Highway 6 and Nelson.
Drivers must avoid the area or delay their journey.
Winter weather conditions are affecting all highways in the top of the South Island, meaning driving conditions are hazardous.
For people heading further south, other highways are also closed due to snow:
Road users must take extra care on the roads. Reduce your speed and avoid sudden braking – it only takes a split second to lose control in wet or icy conditions.
Bad weather can also see roads closed at short notice. Please check road and weather conditions before your journey.