High energy prices likely mean inflation is heating up. Will it push the Fed to hike this month?

Consumer Price Index data due out tomorrow will likely show that inflation heated up in September as energy prices rose.

Economists surveyed by Bloomberg expect a 3.6% jump in annual inflation, up from 3.4% in August. On a monthly basis, prices are expected to be up 0.6% in September from 0.4% a month earlier.

Gas prices are likely to be a particularly large contributor to September's inflation figures. Average prices at the pump hit a record $4.33 last month , according to AAA data, nearly $0.50 above the previous monthly record set in 2023.

What may look more subdued, however, is "core" inflation, which strips out volatile food and energy prices and is watched more closely by Federal Reserve officials. Economists expect core inflation to come in at 2.5% annually in September, a slight acceleration from 2.4% in August. Monthly core inflation is seen ticking down slightly to 0.2%, from August's higher-than-expected 0.3%.

"Wednesday's September Consumer Price Index report is expected to be a rather straightforward print, but no news is not necessarily good news when inflation remains elevated," Realtor.com senior economist Jake Krimmel said in a statement.

Core inflation in line with expectations will likely be enough to convince the Fed to hold rates steady at its Oct. 28 meeting. Following a so-so September jobs report and mixed commentary from Fed officials about the timing of future rate hikes , traders currently see a 76% chance that the central bank leaves rates unchanged this month.

But hotter-than-expected core inflation remains a real risk, many economists say. They point to factors like rising costs of certain core inputs, such as airfare, hotels, and auto parts. And the recent run-up in diesel prices can also flow through to the cost of goods.

"The risk remains that we see limited prospect of a material deceleration in core inflation, and September's CPI report won't fully capture the upside risks ahead," RBC economists led by Mike Reid wrote. And if core inflation stays elevated for a second month in a row, an October rate hike may be back in play.

"A 0.3% core CPI print would likely revive speculation that the Fed may need to continue its tightening cycle in [October]," Bank of America economist Stephen Juneau wrote in a note.

Claire Boston is a Senior Reporter for Yahoo Finance covering housing, mortgages, and home insurance.