No predictions loaded for 2015. This site serves NOAA predictions from its own store, and this period has not been fetched for Sacramento yet. Nothing is estimated or interpolated in its place. NOAA's own page for the station has the official table: tidesandcurrents.noaa.gov.
tidealmanac.site/us/ca/sacramento-9416174/2015
Sacramento, CA tide table 2015 (printable) · Tide Almanac