MetService says damaging winds are expected in Auckland and Northland overnight with heavy rain also predicted across both islands.
Auckland electricity lines company, Vector, says customers also need to brace themselves for power outages over the next two days as the storm hits.
A deep low lying west of the North Island is bringing thunderstorms over Bay of Plenty and Waikato on Sunday night, as well as severe gales in Waikato and the Coromandel Peninsula.
MetService says heavy bursts of rain are also expected from Wellington to north of Blenheim, but the snow warnings it issued earlier in the day for parts of the South Island have been cancelled.
In addition, the forecaster predicts there will be damaging gales in Auckland and Northland before Monday morning.
Vector says it will be on stand-by overnight in case the winds cause havoc to its distribution network.
It is warning customers to prepare for power cuts.