After four months of steadily-decreasing gas prices, the average price of a gallon of gas in metro Atlanta climbed a half-cent overnight to $1.99.

The price increase was the first since early October.

Still, Tuesday morning's average price of a gallon of regular unleaded gas was 26 cents lower than a month ago and $1.22 below the price one year ago, according to atlantagasprices.com, a website that tracks how much motorists pay to fill their tanks.

Prices commonly climb this time of year as refineries shut down for maintenance and to prepare for refining summer blends of gasoline that cost more to produce.

The lowest price reported early Tuesday was $1.81 a gallon at several stations in Cherokee and Henry counties. Statewide, the cheapest gas was $1.69 a gallon at a Costco membership club in Augusta.

The nationwide average early Tuesday was $2.06.