Wholesale electricity prices are rising, as hydro lake levels are just under 80% of the average for this time of year due to a long dry spell in the South Island.
MCo, an electricity industry price index that provides a seven-day rolling average, shows the current price per kilowatt hour is sitting at just over 15 cents.
Power consultant Brian Leyland says that's triple the normal price for this time of year of 5c per kilowatt hour.
Mr Leyland says big users will be affected by rising spot prices and domestic users will be hit in the pocket further down the line.
He says lake levels are now uncomfortably low but it's not time to panic yet.