Contact Energy says hydro storage levels in the South Island have continued to fall in the last three months.
In its monthly report, the energy provider says hydro levels fell from 85% of the mean in December to 72% in January, and to 67% so far in February.
In the North Island, hydro levels have risen by about 10% to 131% of the mean.
Wholesale electricity prices in January averaged $73 per megawatt hour.
The company says electricity and gas customer numbers are flat compared with December but significantly lower than a year ago.