Seasonal adjustment factors
Each year with the release of the January CPI, seasonal adjustment factors are recalculated to reflect price movements from the just-completed calendar year. This routine annual recalculation may result in revisions to seasonally adjusted indexes for the previous 5 years. BLS will make available recalculated seasonally adjusted indexes, as well as recalculated seasonal adjustment factors, for the period January 2013 through December 2017, on Wednesday, February 7, 2018. The revised indexes and seasonal factors will be available at Seasonal Adjustment in the CPI.