National average gas prices are forecasted to be a quarter a gallon less expensive than in the summer, according to AAA. The forecast indicates the national gas price average will drop to $2.70 this fall, with the potential to drop even more. This is more than a quarter cheaper than the year’s recorded high in May of $2.97 a gallon.
Gas prices in 2018 have been higher than 2017, and the year-to-day average gas price is 41 cents more ($2.73).
Year-over-year trends include:
Top ten states with largest difference in gas price averages are mostly on the West Coast, Northeast or Mid-Atlantic states:
California (+57 cents)
Hawaii (+54 cents)
Indiana (+49 cents)
Arizona (+48 cents)
Oregon (+46 cents)
Connecticut (+45 cents)
Rhode Island (+45 cents)
Utah (+45 cents)
Massachusetts (+44 cents).
Four Great Lakes and Central and one Southern state carry the smallest year-over-year difference in gas prices:
South Dakota (+37 cents)
Missouri (+37 cents)
Louisiana (+36 cents)
Iowa (+36 cents)
Nebraska (+35 cents)
The drop in gas prices this fall is due to the switch to the winter-blend gasoline in mid-September. The difference between summer and winter blends has to do with the Reid Vapor Pressure (RVP) of the fuel, which is a measure of how easily the fuel evaporates at a given temperature. A higher RVP evaporates more easily. The winter-blend gas is cheaper to produce and has a higher RVP because the fuel has to be able to evaporate at low temperature for the engine to operate properly.
