Transpower has called for an increase in generation offers from the electricity industry again, with available power expected to fall below 200 megawatts during this evening's peak.
The system operator issued a Customer Advice Notice (CAN) on Tuesday due to higher demand than expected during this evening's 5pm and 7pm peak and less wind generation available than offered.
Tanspower general manager operation Dr Stephen Jay said CANs are a "routine part" of operating the power system, and added low residual situations "typically resolve" as the industry responds to the notice by providing additional generation offers.
He said the situation is being monitored throughout the afternoon and doesn't anticipate any disruptions to consumers.
It was only last Tuesday that the system operator issued a CAN as it experienced the same issue.
Towards the end of last month, Transpower issued a national grid emergency notice following insufficient energy offers and warned of potential power cuts.
Last Monday, Transpower chief executive Alison Andrew told AM she was confident blackouts could be avoided this winter.
"We believe that there is enough, sufficient generation."
She added Transpower's forecast show there may be a few "tight" electricity days in the coming months. Those days could be when generation plants or transmission circuits were down for maintenance.
"I can never guarantee to you that we won't have a power outage - no one can do that - but what I can guarantee to you is that we will work hard as an industry to make sure this is sufficient generation."