Inflation speeds up as gas prices climb, and some details could keep the Fed wary.

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 climbed 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 the 3.6 percent that economists had expected.

After removing food and fuel costs, both of which can jump around a lot from month to month, a core price index climbed 4.3 percent from a year ago. That was less than the previous reading. But on a monthly basis, the core measure climbed faster than economists expected — rising 0.3 percent, up from 0.2 percent in each of the previous two months.

That monthly reading matters because economists watch it for a hint of how much momentum inflation has. The slight pickup came as purchases like car insurance and airfares became more costly.

Economists and investors were closely watching the report, which is the last major data release the Fed will receive before its Sept. 19-20 policy meeting. While central bankers are widely expected to leave interest rates unchanged at their gathering next week, they will probably debate whether one more rate move might be warranted later this 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 that 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 percent, up sharply from near-zero as recently as March 2022. Those higher borrowing costs are meant to gradually slow the economy — but they take time to have their full effect, and are still trickling through to make it tougher and more expensive to use credit to buy a house, lease a car or expand a business.

Policymakers at the Fed want to avoid raising 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.

But the bar for lifting borrowing costs seems to have climbed as inflation has slowed. 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 — which has been helping overall inflation to moderate. Many economists think that a cooling job market with slower pay gains could pave the way for weaker price increases.

And some economists are expecting demand to cool heading into the fall, which could help to weigh down prices across a range of products and services as companies struggle to charge more without losing cautious customers. Among other developments, a return of student loan payments starting in October could crimp household budgets and discourage spending.

Still, Doug McMillon, the chief executive at Walmart, said at a consumer conference this week that he has been surprised by consumer 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 returning to the lower levels that prevailed a year ago. To use the technical terms, it means that he expects disinflation — which is what the Fed is aiming for — but not outright deflation.

“There has been a bit of rebalancing as it relates to higher wages in the country: 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.”