Gas prices slip below $4 a gallon for first time since July

Gasoline prices in the U.S. are below $4 a gallon for the first time in nearly four months.

According to AAA, the national average for a gallon of gasoline was $3.9788 on Tuesday, down from $4.56 a gallon earlier this year.

After the price drop, Patrick De Haan, a petroleum expert at tracking firm GasBuddy, predicts that fuel prices will continue to ease into the Thanksgiving holidays.

Why are prices down?

Gas prices have fallen in recent weeks as filling stations switch from summer-blend fuels to cheaper winter blends. Federal rules require gas stations to sell a summer blend, designed to guard against evaporation, from June 1 to Sept. 15. Outside that period, stations are allowed to use a winter blend, which is cheaper to produce, explaining why prices often fade in the fall.

The switch to the winter blend coincides with a drop in demand, as people take fewer road trips and vacations during the winter months. According to AAA, gas prices fall by around 10 to 30 cents per gallon during the winter months for that reason.

Global oil costs, the main factor determining prices at the pump, have also dipped amid hopes that the midterm elections could open the door to a deal between the U.S. and Iran to end the war.

On Tuesday, Brent crude, the international benchmark, was $TKTK per barrel, down from a recent peak of $113.43 on Oct. 30.