ILLINOIS (WCIA) — You need to prepare for some sticker shock when you get your power bill this summer.

Ameren is warning customers their rates will be going up. They said it is because of issues with global supplies.

They are estimating up to a $13 increase per month on power bills.

Supplies of energy across the country are relatively low right now. And when the supply is low, the demand gets higher, causing a spike in rates.

“All of that is sort of conspiring to result in a pretty steep increase in the overall cost of energy supply, which Ameren Illinois purchases and delivers to our customers and passes through those costs one to one,” said Communications Director at Ameren Illinois Tucker Kennedy.

National organizations that track the power supplies across the country are reporting lower than usual amounts of energy in storage. They are blaming it on the quick transitions to renewable energy.