Gas prices in Denver are sliding toward the $2.50 mark, with some already pushing below that barrier.

Some grocery chains sold at $2.53 a gallon earlier this week, but that included a 10-cent per gallon discount to generous shoppers.

Gasoline prices have been extremely volatile this year, dipping to a low of $2.09 on Jan. 31 and then a record high of $3.34 on May 24.

For now, they are expected to continue going down — unless unpredictable events such as devastating hurricanes or refinery fires squeeze supplies.

"Refineries which feed Colorado are back online and that's the main reason for cheaper gas prices," said Bryant Gimlin, energy risk manager at Gray Oil Co., a wholesale distributor of gasoline in Denver.

Fire at a Texas refinery, flooding at a Kansas facility, and maintenance work at some others crimped gasoline supplies in spring. Coupled with higher crude oil prices, pump prices hit record highs in Colorado in May.

Colorado's two refineries in Commerce City — owned by a Canadian company, Suncor Energy — supply only one-third of the state's 5.5 million gallons a day gasoline demand. A new refinery has not been built in decades.

Gimlin expects gasoline prices to fall below the $2.50-a-gallon mark later this year, closer to Thanksgiving and Christmas.

AAA spokesman Eric Escudero offered what people know but don't necessarily want to hear.

"Just because prices are going down now doesn't mean they won't go up higher in the future, say for the Labor Day travel holiday," he said.

On Tuesday, the average price of regular, unleaded gasoline in Colorado was $2.864 a gallon, according to AAA's daily fuel gauge report. Last month, the average was $3.112.

Colorado's previous record was set Aug. 11, 2006, when the average price hit $3.076. When adjusted for inflation, the highest U.S. average retail gasoline price was $3.079 in March 1981, according to the Energy Information Administration.

chakrabartyg@RockyMountainNews.com or 303-954-2976