As the war in Iran has squeezed energy supplies, its impact is beginning to ripple across sectors that rely heavily on fuel and gas, like travel.

Americans planning to travel this summer are finding far steeper prices than they did a year ago. Federal inflation data released on Wednesday showed airline fares averaged across cities in the United States had rocketed up 26.7 percent in May compared with the same time last year. They were up nearly 3 percent from the month before.

Airlines like United, Delta and American flagged concerns about rising fuel prices in their most recent earnings reports in April, when all three said fuel expenses were up more than 10 percent from the year before.

Hotel rates have also risen about 5 percent since last year, possibly because of increased demand from the FIFA World Cup.

For people traveling on the ground, the picture isn’t much sunnier. Public transportation costs have also swung higher, up nearly 17 percent since last year. That inflation could be moderating, given that it ticked up 0.3 percent from April to May.

While new car prices trudged up about half a percentage point for May, they fell from the month before. Car and truck rental prices have dipped by around 6 percent. Renting a car is cheaper today than it was a year ago, but with motor fuel costs up nearly 41 percent since last year, it’s still going to cost a lot to fill one up.