State-owned generator Mighty River Power has joined the chorus of utility companies blaming the weather for low power production.
The decreased generation has been linked to steep rises in electricity wholesale prices in December, forcing production cuts at the Tiwai Point aluminium smelter and the Tasman paper mill.
Meridian and Genesis Energy say warm, dry conditions and concerns over hydro lake levels have forced their reductions.
Mighty River Power says the drought declared in Waikato this week is reflected by low in-flows in the Taupo catchment.
The company says without more rain, it is not in a position to increase generation from the Waikato hydro system.