GREEN BAY, Wis. (AP) -- Anyone needing proof that it's already been a tough winter can just check their heating bills.

A Green Bay-based utility says the cold caused the typical residential customer's natural gas bill to rise about 17 percent higher than normal in December.

Kerry Spees of Wisconsin Public Service says it's been an "almost brutal winter so far."

That's why the bills are higher even though natural gas costs are running about the same as last year.

The utility has some tips to cut costs.

For example, lowering the thermostat can save about 2 percent on a heating bill for each degree reduced for 24 hours. But lowering it for only a few hours daily won't make much difference.

One way to avoid the season ups and downs of heating bills is to go on a budget-billing program that charges an average monthly rate.