BOSTON -- We're paying more at the pump again with gas prices taking a jump in the past two weeks.

In Lexington, gas prices at a local rest stop of Route 128 ranged from $2.79 for regular to $2.99 for premium.

The reason for the hike is that refiners are switching over to the more expensive summer blends. The national average is now $2.73, which is up 10 cents in the last two weeks. A typical driver will pay an extra $15 a month as a result.

In Massachusetts, the average is $2.71 for a gallon of regular gas, which is a few cents below the national average. In metro Boston and Springfield, prices average a little lower than that, while on Cape Cod and the islands, and Pittsfield, the price point tends to be a little higher.

On Massachusettsgasprices.com, some prices as low as $2.56 for a gallon of regular were found in New Bedford. Some analysts said it may pay to shop around because prices could creep as high as $3 a gallon by spring.