A dry winter is causing a surge in power prices for Flick Electric Co customers in the Upper North Island.
The company sent an email to customers explaining dry conditions had put pressure on the hydro lakes.
Spot prices in the North Island were up to 10.8 cents per kilowatt in June, almost double the previous year's price in the same time period.
"History tells us that dry winter conditions happen once every four or five years, and last from three to eight weeks, so we expect these conditions to be over by mid-August," the letter said.
"But this could all change suddenly if there's a decent rainfall in the right places in the South Island. There's rain forecast for later this week, so it seems the mass finger-crossing happening at Flick HQ may be working."