If you gasped when you opened your Nova Scotia Power bill this month, you are not alone.

The utility says as many as 100,000 customers may have bills that were estimated because of the large amount of snow this winter. Snow banks prevented the company's staff from actually reading many meters, so the power corporation estimated the bill.

"So in their cases, they received an estimated bill and that was based on their usage for the previous year," said Bev Ware, a spokesperson for Nova Scotia Power.

"The bills they are now receiving are based on what they actually did use."

Ware says usage was also higher because it was 10 per cent to 20 per cent colder this winter.

The Nova Scotia Utility and Review Board says it was given some early notice that meter reading was a problem, but didn't know so many customers were affected, says executive director Paul Allen.

However, he adds that estimated bills are allowed and the utility board has no jurisdiction so long as the correct rate is applied.

"I was shocked and upset and wondering why we owed that much," Wolfville resident Tammi Parnell said about her bill.

Parnell said her usual bill is $200. "This most recent bill, more than triple that."

At the Parker Street Food and Furniture Bank in Halifax, staff are hearing about higher-than-average bills, too, even though some people say they are barely using their heat.

"They would just turn the heat in one room or they would just bundle up , wear extra layers of clothing inside the home just to keep themselves warm," worker Cynthia Louis said.

The power company also said meters that were read in one billing period may not have been read correctly.

"We're now finding out with … meter readers going back and being able to get a close-up reading that those readings back in February and March were not accurate. They were under-read … but they were back from the meter at the time so it was difficult for them to see," Ware said.

Whatever the reason, people like Parnell are still trying to come to terms with their bill.

"A little stressed out," she said. "It's not good when you get a bill that big and you're not expecting it."

The power company said it is confident that their systems are working correctly and the right rates have been provided. However, it urges concerned customers to contact them and if there is an error, it will be corrected.