Some gas stations in the metro Indianapolis area today raised the cost of the cheapest gallon of unleaded gas to $2.39, a 10-cent jump from last week and a continuation of an upward trend.

AAA and Oil Price Information Service say the statewide average today was $2.28, and it’s $2.26 in Indianapolis.

But it was clearly on its way up, reports indygasprices.com.

The average in Central Indiana has been steadily climbing since reaching an average low of $1.70 statewide in December. Last Tuesday, many stations jumped from $2.09 a gallon to $2.29.

Then came today’s overnight jump.

We aren’t alone. Fuel prices spiked as high as $2.50 a gallon Monday at gas stations in Kentucky and southern Indiana.

Fuel bargains:

Click here to find the cheapest gasoline prices in the Indy metro area.

Rising pump prices are the norm for May as U.S. refiners switch to more expensive blends of gasoline that are required to meet state and federal clean air requirements.

There are also refineries still operating at reduced levels because of annual maintenance, said Tom Kloza, publisher and chief oil analyst at Oil Price Information Service.

Optimism about an economic recovery, or at least the belief that things may not get worse, have pushed energy prices higher with some expecting a rebound in demand.