Gas prices are creeping back toward $4 a gallon on Whidbey Island.

The cost for a gallon of regular unleaded was $3.999 in Clinton, Bayview, Freeland and Coupeville early Tuesday.

In Greenbank, a sign at the Greenbank Store said the business was temporary out of regular unleaded gasoline.

A spot check of service stations early this week found the lowest prices in Oak Harbor, with a gallon of regular unleaded at $3.799 at the ARCO on Highway 20 and $3.899 at the nearby Safeway.

A gallon of regular unleaded last topped the $4 mark in June on South Whidbey. The previous high above $4 was in summer 2008.

Gas prices across Washington have been slowly climbing over the past month, according to AAA’s Daily Fuel Gauge Report.

The average cost of a regular gallon of gas in the state was $3.781 a month ago. Last week, the average price was $3.869. By Monday, it had risen to $3.887.

A year ago, the average price of a regular gallon of unleaded gas was $3.016.

In the Seattle-Bellevue-Everett area, the cost of a regular gallon of unleaded gas was $3.886 Tuesday, according to the Daily Fuel Gauge Report. That’s up from $3.873 a week ago, and $3.783 a month ago.

A year ago, a gallon of regular unleaded cost $3.007 in the Seattle-Bellevue-Everett area.

The highest reported price in the Seattle-Bellevue-Everett area was on June 22, 2008, when a gallon of regular unleaded was priced at $4.389.