The national average gasoline price increased 1 cent to $2.85 with Hurricane Florence approaching the East Coast with an expected landfall between South Carolina and Virginia later this week.

If the category 4 storm follows its projected path, it would likely have an impact on East Coast gas prices later this week, according to AAA.

Prices remained fairly stable for the week ending Sept. 10, and gasoline demand dipped slightly, according to the U.S. Energy Information Administration.

"A storm like this typically causes an increase in fuel purchases in the market and a slowdown in retail demand," said Jeanette Casselano, AAA spokesperson. "Motorists can expect spikes in pump prices to be brief, but possibly dramatic."

States with the least expensive markets, according to AAA, include Alabama ($2.52), Mississippi ($2.54), Arkansas ($2.57), Louisiana ($2.58), South Carolina ($2.59), Tennessee ($2.59), Virginia ($2.61), Missouri ($2.61), Texas ($2.62), and Oklahoma ($2.63).

States with the largest monthly changes include Michigan (down 12 cents), South Dakota (down 10 cents), Illinois (down 10 cents), Colorado (up 7 cents), North Dakota (down 7 cents), Alaska (down 7 cents), Nebraska (down 6 cents), Florida (down 6 cents), Washington, D.C. (down 5 cents), and Tennessee (down 5 cents).

Meanwhile, the national average price of a gallon of diesel increased six-tenths of a cent to $3.258, which is 45.6 cents higher than a year ago.