As construction’s winter slowdown began, the industry’s unemployment rate worsened in December to 16% from 13.1% in November. But the industry did add 17,000 jobs last month, and its December rate was much improved over the December 2011 mark of 20.7%, the Bureau of Labor Statistics reported.

Those BLS industry-specific rates are not adjusted for seasonal swings. Jobless rates for the highly seasonal construction industry tend to climb in winter months, when the volume of projects dips.

Construction economists said seasonal factors may help explain the rate's rise from November, and mild December weather might have been a reason for the uptick in the number of construction jobs.

The bureau’s latest monthly look at the U.S. employment situation, released on Jan. 6, showed that construction’s non-residential specialty-trade sector gained 20,200 jobs, and residential building firms picked up 2,500 jobs. Those increases were offset a bit by declines in the residential specialty trade, non-residential building and heavy/civil segments.

Architectural and engineering services, viewed as a leading indicator for the construction industry, posted a tiny increase of 500 jobs last month.

Anirban Basu, the Associated Builders and Contractors chief economist, had an upbeat reading of the latest numbers. He attributed the increase in the construction unemployment rate mainly to "seasonal factors" and said it "should not be interpreted as evidence of industry decline."

Moreover, Basu said that with an overall net gain of 200,000 jobs last month, "the U.S. economy is enjoying resurgence, one that has begun to encompass the nation's construction industry." He added, "While major economic headwinds remain, including elevated levels of distressed properties and disciplined lending, the worst appears to be behind the U.S. construction industry."

Ken Simonson, the Associated General Contractors chief economist, said unusually warm weather in many parts of the country probably helped produce December's increase in construction jobs.

Simonson added, "Non-residential construction is clearly driving last month's employment gains. But it is too early to tell whether those gains came because the weather was good enough for crews to keep working well into December or because demand is truly rebounding."