Vector said crews were working through the night to assess the damage and said some assessments and repair plans may not be complete until Thursday.
In Hamilton, 15,000 homes were without power for a while.
Power was still out for some in Waikato early Thursday morning, including around Te Akau and Raglan.
The Desert Road (SH1 Rangipo to Waiouru) closed on Wednesday night due to snow and a detour was in place.
Winds were forecast to remain blustery in many places on Thursday morning, MetService said.
The weather was expected to be pleasant for the long weekend.
RNZ