Diesel will average $3.90 a gallon this year, the Department of Energy said, boosting its most recent price forecast by 4 cents.
Average monthly prices will fall into the $3.80s beginning in July, DOE said in its monthly short-term energy outlook released June 10.
Diesel’s $4 per-gallon March average was the year’s peak, and the price will slide into the mid-$3.80s for the rest of the year until December, when it will decline to $3.81, the report said.
Diesel will average $3.85 in the second half of the year, DOE’s Energy Information Administration said.
Gasoline, meanwhile, will average $3.50 a gallon this year, up 3 cents from last month’s forecast.
Both prices would be slightly lower than a year ago, when diesel averaged $3.92 and gas averaged $3.51.
Prices will continue to slide next year, when diesel will average $3.78 and gas will drop to $3.38, EIA said, citing projected longer-term lower oil prices.
EIA boosted its 2014 oil-price forecast to $98.67 per barrel, up from last month’s $96.59 forecast, but said oil will recede in 2015 to $90.92 per barrel.
It said the monthly average regular gasoline retail price peaked at $3.67 per gallon in May, and will fall to $3.54 per gallon on September.
DOE’s monthly short-term outlook often lags its weekly price survey. This week, diesel fell 2.6 cents to $3.892 — its biggest single-week decline in more than a year and the first time it has been below $3.90 since January.
Crude oil futures closed at $104.41 a barrel on the New York Mercantile Exchange on June 9, the highest settlement price since March 3 and just the sixth time oil has finished over $104 since then, Bloomberg News reported.