“Core” C.P.I., which more closely reflects underlying inflation by removing volatile food and energy prices, also showed little improvement. It rose 0.4 percent from December or 3.3 percent on a year-over-year basis, both higher than economists expected. The monthly increase in core prices was the highest since April 2023.

Federal Reserve Chair Jerome Powell said the latest consumer price data show that while the central bank has made substantial progress toward taming inflation, there is still more work to do.