Every 5, 6, or 11 years, taking into account leap years.
Eve means "before" and naturally Christmas Eve is the day before Christmas.
December is a whole month, Sunday is just a day so 'December" can't fall on any day of the week as there are 4.25 weeks in the month. If you we're really asking how often Christmas falls on Sunday, since the millennium Christmas has so far been on a Sunday in years 2005 and in 2011; and in 2016 Christmas will again be on Sunday.
Christmas Day will be on a Sunday in 2011.
Christmas is always on the 25th of December so the day of the week changes every year. Christmas 2011 was on a Sunday so logically it should be on a Sunday in 2018 but because of leap years the next time Christmas will fall on a Sunday will be 2016. The pattern does eventually repeat but not for many years.
In 1921 Christmas Day was on a Sunday.
Sunday
Sunday
Sunday
Christmas was on a Sunday in 2011.
The next year in which Christmas day will fall on a Sunday will be in 2016.
In 1968 Christmas Day was on a Wednesday In 1969 Christmas Day was on a Thursday In 1970 Christmas Day was on a Friday In 1971 Christmas Day was on a Saturday In 1972 Christmas Day was on a Monday In 1973 Christmas Day was on a Tuesday In 1974 Christmas Day was on a Wednesday In 1975 Christmas Day was on a Thursday In 1976 Christmas Day was on a Saturday In 1977 Christmas Day was on a Sunday In 1978 Christmas Day was on a Monday In 1979 Christmas Day was on a Tuesday In 1980 Christmas Day was on a Thursday In 1981 Christmas Day was on a Friday In 1982 Christmas Day was on a Saturday In 1983 Christmas Day was on a Sunday In 1984 Christmas Day was on a Tuesday In 1985 Christmas Day was on a Wednesday In 1986 Christmas Day was on a Thursday In 1987 Christmas Day was on a Friday In 1988 Christmas Day was on a Sunday In 1989 Christmas Day was on a Monday In 1990 Christmas Day was on a Tuesday In 1991 Christmas Day was on a Wednesday In 1992 Christmas Day was on a Friday In 1993 Christmas Day was on a Saturday In 1994 Christmas Day was on a Sunday In 1995 Christmas Day was on a Monday In 1996 Christmas Day was on a Wednesday In 1997 Christmas Day was on a Thursday In 1998 Christmas Day was on a Friday In 1999 Christmas Day was on a Saturday In 2000 Christmas Day was on a Monday In 2001 Christmas Day was on a Tuesday In 2002 Christmas Day was on a Wednesday In 2003 Christmas Day was on a Thursday In 2004 Christmas Day was on a Saturday In 2005 Christmas Day was on a Sunday In 2006 Christmas Day was on a Monday In 2007 Christmas Day was on a Tuesday In 2008 Christmas Day was on a Thursday In 2009 Christmas Day was on a Friday In 2010 Christmas Day was on a Saturday In 2011 Christmas Day was on a Sunday In 2012 Christmas Day was on a Tuesday
Christmas this year will be on a Sunday