Market Data

Gasoline's Seasonal Curve: The Cheapest and Priciest Months to Fuel a Fleet

An original ranking of average retail gasoline prices by calendar month from the EIA weekly history, exposing the summer-driving premium.

Retail regular gasoline consistently peaks in late spring and summer and troughs in winter, and against that seasonal curve the current $3.78/gal (as of Jul 6, 2026, per the EIA weekly survey) can be read properly: not as a raw number, but as a position on a curve that repeats every year. In the archived window, the priciest calendar month has averaged $4.48 (May) and the cheapest $3.78 (July), a spread a fleet can plan around.

What the archive shows

Averaging the archived weekly prints by calendar month, May stands as the most expensive month at $4.48 on average, and July the cheapest at $3.78, a gap of $0.70 per gallon between the fleet-fueling extremes of the year within this window. The full weekly series has ranged from $3.78 (Jul 6, 2026) to $4.50 (May 11, 2026). These figures are computed fresh from the live archive each time this page rebuilds, so the ranking updates as new weekly prints arrive and the archived window lengthens.

Why the curve exists

Three mechanisms build the seasonal shape, and none of them is going away. First, summer-blend gasoline: environmental rules require lower-volatility fuel roughly May through September, and it costs more to refine, adding several cents to a dime at the transition. Second, driving-season demand: vacation miles lift consumption from Memorial Day through Labor Day, pulling prices up exactly when the costlier blend is mandatory. Third, refinery maintenance: plants schedule turnarounds in spring and fall shoulder seasons, tightening supply just as the blend switch happens, which is why the spring run-up often starts before summer demand actually arrives. Winter reverses all three: cheaper blend, fewer miles, steadier refinery output.

U.S. regular gasoline, retail, Jul 6, 2026: $3.78/gal. Ranged from $3.78 (Jul 6, 2026) to $4.50 (May 11, 2026) across the archived history. The latest print sits in the lower third of that range.

The seasonal curve is built from regulation, vacations, and refinery calendars, three forces a fleet cannot change but can absolutely schedule around.

Using the curve in a fuel plan

A fleet burning 37,500 gallons a year uses about 3,125 gallons a month. At the archived monthly averages, the same month of fueling costs about $2,195 more in May than in July. Miles mostly cannot move to cheaper months, but plenty of decisions can: schedule tank-topping and bulk purchases into the trough months, time annual fuel-card negotiations away from the spring run-up, set customer surcharge tables with the seasonal premium built in rather than reacting to it, and sanity-check any month's budget variance against the curve before blaming routes or drivers. Seasonality is the one fuel-price move that arrives on schedule; the only mistake is planning as if it will not.

Use the route miles cost calculator to price your monthly mileage at trough and peak seasonal averages and size the swing for your own fleet. Plan fueling by the mile

Published 2026-07-13.