COLUMBIA -- South Caroline Electric & Gas customers who kept their homes toasty in January are feeling the heat now that their bills are coming due.

A brutally cold month resulted in far higher power bills than in December. While the Cayce-based utility says there is no such thing as an average electricity bill, it said the cost of heating an older, large home with a heat pump last month would have been about 40 percent higher than in December.

That's despite a weather normalization program that was put in place last year, intended to blunt sharp swings in heating bills during severe changes in the weather.

The utility says that program helped keep the cost down some by lowering the cost of a kilowatt hour of electricity to its customers. Just how much varied from customer to customer, based on their heating habits, said SCE&G, a division of Cayce-based Scana Corp.

Bills mailed to SCE&G customers last month were about 2.5 percent lower than in January 2010, the company said, even though electricity use in January 2011 was up 5.2 percent over a year ago.

"The (electric) weather normalization adjustment is the reason for that," SCE&G spokesman Eric Boomhower said. "Otherwise, the bills would have been up because consumption was up."

Cold weather drove electricity use to two new winter peak records in January, first on the 11th, only to be broken three days later when SCE&G customers devoured 4,872 megawatts of the juice, as Midlands residents struggled to stay warm during an ice and snow storm.

The weather normalization program lowers the cost of a kilowatt hour of electricity when temperatures vary greatly, higher or lower, from their 15-year averages.

But January was so cold that savings on the cost of a kilowatt hour easily were negated by the urge, or need, to turn up the thermostat.

When thermostats are turned up in homes heated by heat pumps, which Boomhower said most South Carolina homes have, it has a direct effect on power consumption, reflected in monthly bills.

"The biggest user of electricity in your home is your heating and cooling system," Boomhower said. "So, your energy costs can fluctuate significantly from month to month or year to year, depending on outside temperatures."

Other variables also can enter into monthly bills, including the differing billing cycles that the utility uses, Boomhower said. Depending on your billing cycle, some of the coldest days of a month may or may not show in that month's bill.

The closing of schools due to the colder weather, which also forced some adults to miss work, also played a role in January's higher bills. Children and parents at home during the day meant more daylight hours of energy use.

"We realize the recent cold weather and resulting increase in demand for electricity will mean higher bills for many customers," Boomhower said.

"We encourage customers who may need special assistance with paying their bill to call us at 800-251-7234, or come into one of our business offices and talk with us about the programs and options that may be available to help."