Karen Taylor says she doesn't spend a lot of time staring at her hydro meter. But when her Hydro bill arrived last month, she definitely gave it a double take.

"We were quite shocked," said Taylor. "It was really, really up there."

It was triple the expected amount: $300 instead of $100.

"We called and they said the amount was an estimated amount," she said.

It was an inaccurate estimate, and Taylor is far from the only customer affected.

Wednesday Manitoba Hydro alerted customers it was working to correct a problem that had led to high estimated bills. Hydro says the problem is the result of a combination of factors, including the province’s hot summer.

"It's been so warm lately, it's almost outside the range of experience of our billing system, the algorithmm" said Scott Powell, a spokesperson for the utility.

Hydro says the issue is worse in cases where there hasn’t been enough meter readings to establish a customer’s history of energy usage. When that happens, the algorithm puts a lot more weight on weather factors, which led to some wonky estimates.

"Now, any bill over 400 dollar where that appears to be much higher than that person’s normal summer consumption," said Powell. "We're examining those manually."

Powell says if your bill seems wrong, check your meter, and then call Hydro.

Manitoba Hydro says customers who already received and paid a bill based on an incorrect estimate will see a correction in the next bill. That will be based on an actual meter reading, not an estimate.