Gas prices are at their highest prices in more than a year in Chicago.

Gas costs an average of $2.71 per gallon in the city as of Friday, according to GasBuddy.com. That’s 17 cents higher than the national average of $2.54 per gallon, though the national price is also at its highest point in more than a year.

Gas prices in Chicago have jumped by 20 cents just since Aug. 20, according to GasBuddy.

There are a variety of reasons for the recent increase seen around the nation: Sellers are expecting higher demand for the holiday weekend, refineries and pipelines have faced shutdowns from tropical storm Harvey and “supply levels” have tightened in the Gulf of Mexico, according to an American Automobile Association news release

A “major” pipeline that flows north to Chicago has faced issues due to damage from the storm, according to The Associated Press.

The line can carry 660,000 barrels per day, and about 350,000 of which typically go to the Chicago area, according to Reuters.

Gas prices should drop by mid- to late September, according to AAA, as refineries in Texas aren’t expected to be out of commission for long.