NEW YORK (TheStreet) -- Goldman Sachs (GS - Get Report) , which has said for months that the Federal Reserve would probably raise interest rates before Christmas, is no longer quite so sure.

Whether that indicates a visit by Santa Claus -- or the Grinch -- depends on your perspective. 'Bond King' Bill Gross, for instance, has said average Americans are being "burned alive" by low interest rates because they're not getting the returns necessary to fund needs from retirement expenses to education.

A rate hike in December remains the most likely scenario, but Jan Hatzius, lead economist for New York-based Goldman, noted that the odds of a later increase are climbing amid weaker economic data, including job growth in September that lagged behind analysts' estimates.

"Standard monetary policy rules might justify a continuation of the current zero-rate policy for much longer, well into 2016 or potentially even beyond," Hatzius wrote in a report this week. 

The September jobs report, which was released on Friday, showed the U.S. added 142,000 jobs last month compared with an estimate of 203,000 from analysts. Still, the unemployment level is holding steady at 5.1%, where it stood in April 2008, just months before the financial crisis. That's a significant improvement from a 2009 high of about 10%.

Many traders had initially speculated that the central bank would begin raising rates in September, but changed their minds after extreme market volatility in August as growth in China, the world's second-largest economy, slowed. That prompted concerns that deterioration in China would hurt American trading partners, eventually crimping gains in the U.S.

Although the Fed typically takes a broader view of the economy than a few weeks of volatile equity markets, Federal Reserve Chair Janet Yellen acknowledged that the weeks leading up to the monetary policy committee's September meeting weighed on its decision.

Considerably uncertainty surrounds "the outlook for economic activity," Yellen said in a speech at the University of Massachusetts-Amherst in late September. "We cannot be certain about the pace at which the headwinds still restraining the domestic economy will continue to fade. Moreover, net exports have served as a significant drag on growth over the past year and recent global economic and financial developments highlight the risk that a slowdown in foreign growth might restrain U.S. economic activity somewhat further."

Prior to the Fed's September meeting, Hatzius's team found that financial conditions had tightened since early August. Among the factors the team reviewed were: credit spreads, equity prices, and the rising value of the U.S. dollar. Taken together, they showed the economy tightened by 50 basis points since the beginning of August, a shift roughly equivalent to three rate-hike cycles.

Keeping rates low for a longer period, and then raising them more rapidly, would curb the immediate risk that a change would hurt the economy, Goldman noted. "The growth and labor market numbers over the next couple of months are therefore likely to be even more important than usual," Hatzius said.

Yellen noted that the central bank would be paying close attention to such data, though she maintained an increase before the end of the year was likely.

"If the economy surprises us, our judgments about appropriate monetary policy will change," Yellen said.