The price of diesel fuel across the nation rose on average three cents on 12/4/2017. The retail price climbed to $2.915 a gallon. It is the highest price of diesel since March of 2015. The price is 47.2 cents more than it was at this time last year. California is again the highest region in the country at $3.585 a gallon. The lowest is in the Gulf Coast region where the price is $2.713.