While U.S. average prices for diesel and gasoline stayed relatively flat week-over-week, the cost of both fuels soared at pumps in New England and the Central Atlantic regions of the country, according to data tracked by the Energy Information Administration (EIA).

The average U.S. price for diesel decreased 7/10ths of a penny this week to $3.911 per gallon, although that makes diesel 8.3 cents per gallon more expensive compared to the same time period in 2012, EIA noted.

The cost of diesel fell precipitously in the Rocky Mountain region, dropping 5.8 cents to $3.668 per gallon; the cheapest price for diesel anywhere in the U.S., with the Gulf Coast ($3.837 per gallon) and the Midwest ($3.87 per gallon) representing the second and third lowest cost regions for that fuel in the U.S., the agency said.

By contrast, diesel soared to $4.153 per gallon in New England and to $4.107 per gallon in the Central Atlantic region, making both areas home to the highest diesel prices in the U.S., exceeding even California ($4.048 per gallon), according to EIA’s numbers.

New England and the Central Atlantic region were also home this week to the highest gasoline prices in the nation, hitting $3.516 and $3.519 per gallon, respectively – again higher even than gasoline sold on the West Coast ($3.488 per gallon), the agency’s data indicated.

Overall, the U.S. average for gasoline crept up 1/10thof a penny this week to $3.299 per gallon, which is 8.3 cents cheaper compared to the same time period last year. Gasoline prices declined the most in the Rocky Mountains (an 8.1 cent drop to $2.935 per gallon) and the Midwest (7.8 cents to $3.142 per gallon) which were both home to the cheapest gasoline in the country, EIA said.