South Island drivers are being urged to consider delaying their trips, until bad weather has passed.

Heavy snow is expected tonight and into tomorrow in the Canterbury High country.

Transport Agency Journey Manager Tresca Forrester says there'll also be heavy rain in the Kaikoura Ranges.

"There is about 30 to 40 cm of snow forecast through the Lewis Pass in the next 24 hours, so really advising to think about if you have to travel, and if you do, be prepared."

State Highway One North and South of Kaikoura is closing early tonight at five PM.