Yellen’s speech to the World Affairs Council of Philadelphia at 12:30 p.m. ET will address the economy and monetary policy, and is the last public comment by U.S. central bankers before their June 14-15 meeting.

The chances of a rate hike at that meeting were all but killed by a report showing the U.S. economy added only 38,000 jobs in May, muting recently upbeat data on consumer spending and overall growth. A sensitive British vote on European Union membership set for later this month is another reason for the Fed to wait.

Economists now see July or September as more likely timing for a quarter-point policy tightening, after the central bank lifted off from near-zero rates in December.

Yellen could note that the May report does not necessarily suggest a more permanent gloom for the labor market, where unemployment at 4.7 percent is at its lowest level since the beginning of the recession. On rates, she could repeat her line from a week-and-a-half ago that a rise could be appropriate “probably in the coming months.”

Millan Mulraine, deputy chief economist at TD Securities in New York, said he expects the Fed Chair to reiterate a “relatively upbeat outlook on growth and inflation, while continuing to emphasize the need for caution.”

While likely keeping a July rate hike on the table, Yellen “will emphasize that any decision to act will be highly data-dependent,” he wrote in a note to clients.

The worst monthly jobs growth in more than 5-1/2 years comes as other parts of the world’s largest economy appear to have rebounded from a sluggish winter. U.S. inflation remains below a 2 percent target but has shown signs of stability.

Earlier on Monday, Boston Fed President Eric Rosengren, a voter on policy this year, said that while rate hikes are on the horizon, the central bank will need to determine whether the employment report “is an anomaly or reflects a broader slowing in labor markets.”