Unexpected refinery maintenance has caused prices in some areas to rise slightly, but gas prices are down on average.

The national average price for regular unleaded gasoline has dropped for nearly two weeks after a brief spike during September, according to the information collected by AAA.

Unleaded gasoline was selling for $2.23.5 cents per gallon this week, AAA reported. The average price represents a decrease of two cents per gallon compared to one week ago, but remains five cents more than last month.

Drivers across the country continue to see savings at the pump and are paying an average of three cents less per gallon year-over-year while the price of crude oil remains well below its historical highs, AAA said.

However, prices continue to fluctuate in some parts of the country. Additionally, work continues to replenish supply in areas hit by Hurricane Matthew.

Several refineries across the country are addressing planned and unplanned facility maintenance, putting upward pressure on prices is some area.

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Volatility in the Midwest placed four states in the region at the top of the list for biggest weekly declines: Indiana where prices fell by 14 cents, Ohio where prices dropped by 12 cents, Michigan where prices dropped 10 cents and Illinois where prices fell 8 cents, AAA said.

The West Coast, according to AAA, remains the most expensive market for gasoline, including the only six states where drivers are paying more than $2.50 on average, including California $2.78 per gallon, Washington at $2.71 per gallon, Alaska at $2.63, Oregon at $2.52 and Nevada at $2.51.

The Gulf Coast is also recovering from a week long shutdown of the Pasadena, Texas refinery. The fluid catalytic cracking unit was restarted at the refinery last Monday after it was taken out of service for unplanned repair on a leaking valve.

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Contracts for crude oil continued to react to last month’s announcement that the Organization of Petroleum Exporting States was working on a plan to cut production.

While the market price of oil increased briefly by the end of last week, crude oil prices had dipped back to less than $51 per barrel as a result of continued skepticism about both the plausibility of a plan being agreed to and the implementation of a production freeze, analysts said.

The relatively low price of oil has sent shock waves through the energy industry and added to the volatility on Wall Street where traders will continue to watch discussions surrounding the upcoming November meeting.

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At the close of Friday’s formal trading session on the NYMEX, WTI was down 9 cents to settle at $50.35 per barrel, which would leave the price of gasoline at the current level for the foreseeable future.