Annual revisions to jobs data and disruptions related to the catastrophic Los Angeles fires and severe winter storms are likely to be reasons behind the slump in job gains.

The gain in jobs was lower than expected, but the job counts for November and December were revised upward by a combined 100,000.

U.S. employers added 143,000 jobs last month, somewhat fewer than forecast, while unemployment fell to 4 percent and hourly earnings rose.

U.S. job growth slows sharply in January, with payrolls rising by 143,000, well below expectations of 170,000. Despite weaker hiring, the unemployment rate unexpectedly drops and wage growth accelerates.