Federal Reserve Bank of San Francisco President John Williams said Friday the U.S. economy remains on a solid path that will open the door to interest-rate increases in the summer.

In an interview with CNBC, Mr. Williams said, "I see a lot of strength in the domestic economy," adding there's "a lot of momentum for very good growth." He indicated he is not worried by the unexpectedly soft 2.6% fourth-quarter gross domestic product reading reported earlier Friday, and predicted 2015 will see activity rise by about 3%. Mr. Williams also expects to see the economy near "full employment" by year-end, with the jobless rate hitting 5% from its current 5.6% level.

All of that opens the door for the Fed to raise rates off their current levels near zero. "Around midyear is a good guess for when we are getting around that point that raising rates will be appropriate," Mr. Williams told CNBC. "I'm not predicting it will be June or any particular meeting, but I think we are getting closer to that point" when the Fed can start to act, he said.

Mr. Williams is a voting member of the monetary policy-setting Federal Open Market Committee. That body met earlier in the week. It continued to prepare the way for rate increases, but signaled patience in terms of when it would actually move. Most officials expect to see rates increase this year, with key officials favoring the middle of the year. Mr. Williams has for some time pointed to summer as the most probable time to boost rates.

Mr. Williams allowed that inflation levels well under 2% were a "big story" for the Fed. He continues to believe that after a weak start to the year on oil-related factors, job market gains and signs of rising wages will start to push inflation back toward 2%, a level he sees being attained by the end of 2016.

The Fed should be considering rate rises because it's getting close to hitting its job goal, Mr. Williams said. That inflation is short of target shouldn't be a huge issue, because even a modest move higher on rates would still leave rates at historically low and very stimulative levels.

Write to Michael S. Derby at Michael.derby@wsj.com

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