Wednesday. See the link for an online calendar.
May 31, 1934 fell on a Thursday.
December 31, 1934 fell on a Monday.
August 31, 1934 fell on a Friday.
March 31, 1934 fell on a Saturday.
Wednesday
March 31, 1934 fell on a Saturday.
31 October 2001 was a Wednesday.
31 October 1994 was a Monday.
31 October 2006 was a Tuesday.
31 October 2004 was a Sunday.
October 31, 1979 was a Wednesday
October 31 1952 was a Friday.