Lines company Orion said power was still off to nearly 2800 homes in Canterbury early Friday.
Affected townships includes Darfield, Horarata, Coalgate, Sheffield, Springfield, Lake Coleridge, Kirwee, and Glentunnel.
Widespread snow also caused power outages overnight in South Canterbury, affecting homes from Cave, through to Fairlie, Tekapo and Mt Cook.
Residents should prepare for an “extended outage”, a spokesperson said.
“We will restore supply as soon as possible. Please treat any downed or low wires as live.”
The NZ Transport Agency says highways were reopening as contractors worked to clear up to a metre of snow in areas. The Haast Pass (SH6) reopened around 1pm. Chains were called essential on the Lindis Pass, State Highway 8 from Omarama to Tarras. State Highway 80 (Mount Cook Rd) and SH 79 Geraldine to Fairlie remained closed at 1pm.