North American light-vehicle production will continue to climb on an annual basis, reaching a 12-year high in 2014, but year-over-year comparisons will begin to narrow as the industry wraps up 2012.

WardsAuto expects first-quarter 2013 production to fall slightly from the same year-ago period before reversing course with year-over-year increases by quarter through the end of 2014.

The early-2013 decline can be blamed on the calendar. Plants operating on normal 5-day workweek schedules, which constitute the majority of them, will have two fewer work days in January-March 2013 compared with the same period a year earlier. If workdays were the same, there would be a slight gain over first-quarter 2012.

There are more days in 2012 because of the added leap-year day in February and because Easter holiday shutdowns that came in the second-quarter month of April, vs. March in 2013.

Still, gains are narrowing now that auto makers have aligned inventory more closely with demand.

Production has risen year-over-year in every quarter since a 20.9% decline in third-quarter 2009. Increases hit double-digit territory at the end of 2011 following a slowdown in the second and third quarters of last year, when several manufacturers faced depleted resources resulting from the tsunami that hit Japan and flooding in Thailand.

Even though the effects of those disasters persisted at the end of the year, fourth-quarter 2011 production was able to muscle a 15.8% increase. That was followed by a 17.5% rise in first-quarter 2012 and a robust 27.4% gain in the April-June period.

After the second-quarter peak, production will slow to a forecast 11.9% increase in the third quarter and 3.9% in the final three months of 2012.

Production for 2012 is expected to finish at 15.0 million units, 14.9% above 2011’s 13.1 million, and marking the first time output will have hit the 15 million mark since 2007.

Although forecast production for January-March is pegged at 2.1% below like-2012, output for full-2013 will increase 2.2% to 15.4 million, followed by a 4.2% gain in 2014 to 16.0 million – the highest calendar-year total since 16.4 million in 2002.