WASHINGTON — After two months of blockbuster gains, U.S. employers slowed their hiring in August to a modest increase of 151,000, reducing the likelihood that the Federal Reserve will raise interest rates when it meets this month.

The unemployment rate remained 4.9 percent for a third straight month, the Labor Department said Friday in its monthly jobs report.

August’s job gain was far below July’s 275,000, which was the most in eight months, and June’s 271,000. Even so, over time, the current pace of hiring is enough to lower the jobless rate.

The figures might have been held back by temporary factors, such as layoffs by automakers while plants are being retooled for new models. The government tries to adjust for such seasonal changes but often struggles to do so accurately.

Over the past five years, August job growth has been revised up by an average of 70,000 in the following months. As a result, Fed policymakers may want to await further economic data before acting to make borrowing more expensive. If the Fed doesn’t raise rates after it meets Sept. 20-21, most analysts expect it to do so in December.

They “will want to wait another couple of months, to ensure the data does rebound in September and that August is revised higher,” Paul Ashworth, chief U.S. economist at Capital Economics, said in a research note.

The slowdown in hiring last month appeared to please stock investors, who likely see a diminished prospect of a Fed rate increase this month. Higher borrowing rates tend to weigh down stock prices. The Dow Jones industrial average was up 85 points in mid-day trading.

Hiring had been robust earlier this summer, with job growth averaging 232,000 for the past three months. Those gains appeared to make consumers more confident and willing to spend, potentially accelerating the economy’s growth in the second half of this year after a sluggish start to 2016.

In August, though, hiring weakened across most major industries, and employers cut workers in manufacturing, construction and mining. Job growth slowed sharply in professional and business services, a category that includes higher-paying jobs such as engineers, accountants and architects as well as temporary jobs, which usually pay below-average wages. Temp help firms shed 3,100 positions.

If a relatively tepid pace of job growth keeps the Fed on the sidelines for longer, the continuation of ultra-low rates could sustain the economy’s expansion, some analysts suggested.

“This is a healthy thing if the gains slow down a little bit, because that reduces the risk that the Fed will quickly raise rates and choke off the expansion,” said Josh Wright, chief economist at iCIMS, a recruitment software company.

Still, modest hiring means it could take longer to fully heal the scars of the Great Recession.