Federal Reserve officials are likely to remain wary about the outlook for inflation after a report released Wednesday: Overall price increases sped up because of a pop in gas prices in August, and a more closely watched index that strips out volatile food and fuel prices climbed at a faster monthly pace than expected.

The consumer price index climbed 3.7% in the year through August, the report showed. That was both faster than the 3.2% July reading and slightly quicker than economists had expected.

After the removal of food and fuel costs, which are volatile, a core price index slowed on an annual basis but increased faster than economists expected on a monthly basis — rising 0.3%, compared with 0.2% in both June and July. That pickup came as a range of services, including car insurance and airfares, became more costly. The monthly reading matters because economists monitor it to get a sense of inflation’s momentum, and the acceleration in August was the first in six months.

Fed policymakers have been careful to avoid declaring victory over rapid inflation even as price increases have cooled notably this summer, providing some breathing room for consumers, who have been struggling to keep pace with relentlessly heftier bills. The fresh figures underscored the reason for the Fed’s reticence: Inflation may be decelerating, but the process of fully reining it in remains a bumpy one.

The report was the last major data release that Fed policymakers will receive before their policy meeting next Tuesday and Wednesday. While central bankers are still widely expected to leave interest rates unchanged at the gathering, inflation’s staying power could help fuel a debate about whether they should consider raising rates once more before the end of the year.

“The Fed’s been a little more cautious on the descent in inflation, just because they’ve been burned earlier in the cycle,” said Sarah House, a senior economist at Wells Fargo. She expected the central bank to hold off on a rate move at its upcoming meeting but said the fresh reading underscored that higher rates are likely to remain in place for some time.

“We’re getting hints that inflation is going to remain somewhat stickier,” she said.Fed officials have already raised interest rates to a range of 5.25% to 5.5%, up sharply from near-zero as recently as March 2022. Those higher borrowing costs are meant to gradually slow the economy — making it tougher and more expensive to use credit to buy a house, lease a car or expand a business. But they take time to have their full effect.

Policymakers at the Fed want to avoid lifting rates by so much that the delayed effects add up to tank economic growth. But they also want to avoid doing too little and allowing inflation to become a lasting feature of the U.S. economy.

Central bankers will release a fresh set of economic projections after their meeting next week. Those could show that they still expect to make one more quarter-point increase this year, before lowering rates by the end of 2024, some economists think.

The latest inflation report “keeps the possibility of another rate hike later this year” alive, said Kathy Bostjancic, chief economist for Nationwide Mutual.

Fed officials are likely to keep a watchful eye on inflation at a moment when a key measure of services prices outside of rent has begun to pick back up, she said. Still, when it comes to actually following through with another rate move, she said, “the hurdle is high.”

The bar for lifting borrowing costs seems to have climbed over the course of the summer as a boiling job market has cooled to a simmer, and as inflation has come down from the heights it reached last summer, when it peaked above 9%.

Fed Chair Jerome Powell was saying as recently as June that Fed officials thought it was “likely that some further rate increases will be appropriate this year.” But since the Fed’s move in July, he has toned that down. He said in late August that officials “are prepared to raise rates further if appropriate.”