Federal Reserve officials are likely to remain wary about the outlook for inflation following 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 rose 3.7 percent in the year through August, the report showed. That was both faster than the 3.2 percent July reading and slightly quicker than what economists had expected.

After removing 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 percent, compared to 0.2 percent 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 Sept. 19-20 policy meeting. 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 were 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 percent, 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 American economy.

Central bankers will release a fresh set of economic projections following 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 percent.

Jerome H. Powell, the Fed chair, 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.”

John C. Williams, the president of the Federal Reserve Bank of New York and an influential official, recently said that policy is in a “good place” and that the question is “do we need to maybe raise rates” again.

The Fed has two more meetings this year after the September gathering, with policy votes in early November and mid-December. The central bank will receive one more Consumer Price Index inflation report before its November gathering, on Oct. 12.

Some factors could push inflation higher before the end of the year — or, at any rate, make it harder for inflation to slow down. New data and a methodological change could push up health insurance inflation in the Consumer Price Index measure starting next month, for instance.

On the other hand, rent growth continues to slow — at least on an annual basis. That is helping to pull down the overall numbers, because housing makes up a big chunk of inflation.

And some economists are expecting consumer demand to cool heading into the fall, which could help weigh down prices across a range of products and services as companies struggle to charge more without losing cautious customers. Job openings are less plentiful and wage growth is slower, and a return of federal student loan payments starting in October could crimp household budgets and discourage spending.

Yet Doug McMillon, the chief executive at Walmart, said at a conference this week that he had been surprised by consumers’ resilience this year, and that a solid start to back-to-school shopping boded well for the holiday season.

He also said that while he expects prices to climb more slowly for many products, he doesn’t see them falling to the levels that prevailed a year ago. To use the technical terms, that means that he expects disinflation — which is what the Fed is aiming for — but not outright deflation.

“Inflation and higher prices are kind of with us; we’ll see disinflation,” he said. “But not all the way back to deflation, I don’t believe, certainly not in the short-term.”