The southern hydro lakes are filling up. Heavy rain in the Southern Alps and the spring thaw has pushed current levels past 56%.
Low lake levels forced the adoption of a power savings campaign this winter.
MCo senior pricing analyst Ashley Milkop says the next few months are critical.
Significant inflows have boosted the lakes since August. Electricity spot prices have fallen from $800 per megawatt hour in June to about $50 on 15 October.
Mr Milkop says that has taken the pressure off big users of electricity.
However, domestic prices have not fallen because the power retailers have to repay the cost of buying power over winter on the electricity spot market, when it was expensive.