Lansing drivers are paying $4.29 a gallon for regular gas, a 17-cent jump in one week that puts the capital city well above the national average and near the top of Michigan's price rankings.

GasBuddy's survey of 177 Lansing stations, published Monday, Aug. 17, found prices 27 cents higher than the $4.02 national average. AAA separately pegged Lansing at $4.32, just a penny behind Ann Arbor and Jackson, which were tied for the state's most expensive gas at $4.33.

A year ago, Lansing's average was $3.05. Statewide, filling a 15-gallon tank costs about $64 at Michigan's average of $4.27, roughly $13 more than the peak price last August, according to AAA.

The cheapest Lansing station was $3.98 a gallon on Sunday, Aug. 16; the priciest was $4.44.

Why prices keep climbing

Two forces are squeezing supply. Iran has kept the Strait of Hormuz closed since the U.S.-Israel war with Iran began in late February, choking off a waterway that previously carried one-fifth of the world's oil. A 60-day U.S.-Iran ceasefire expired Monday, Aug. 17, without a diplomatic breakthrough, according to The Jerusalem Post.

Meanwhile, Ukrainian strikes have knocked out an estimated 40 percent of Russia's refining capacity, Forbes reported Aug. 14. Russia halted diesel exports in July and extended that pause through year's end. U.S. diesel inventories sit 10 percent below the five-year average.

Patrick De Haan, head of petroleum analysis at GasBuddy, said the closure of the Strait and ongoing Ukrainian attacks on Russian refineries kept upward pressure on the market. He noted that diesel felt the pressure even more acutely, with the national diesel average climbing to $5.48 a gallon.

De Haan had cautioned on Aug. 11, when Michigan prices briefly dipped below $4, that upward pressure on fuel prices could return quickly if the Strait remained closed. Prices rose 17 cents in Lansing over the following week.

What's ahead

AAA Michigan spokeswoman Adrienne Woodland said the relief drivers felt the prior week was short-lived, with pump prices reversing course and climbing by double digits.

GasBuddy's report noted that a seasonal switch to cheaper winter-blend gasoline in the coming month could offer some relief. But De Haan said the two dominant challenges facing motorists show no signs of resolving soon, and "the path for gas and diesel prices remains tilted to the upside."

WTI crude oil settled at $84.50 a barrel on Monday, Aug. 17, up 2.5 percent.