Federal Reserve Chair Jerome Powell on Friday opened the door ever so slightly to lowering a key interest rate in the coming months, but gave no hint on the timing of a move and suggested the central bank will proceed cautiously as it continues to evaluate the impact of tariffs and other policies on the economy.

Jerome H. Powell said the “balance of risks” across the economy had started to shift, raising the odds the central bank lowers borrowing costs at its next meeting in September.