Wednesday.
Jan 31st 1968 was a Wednesday.
It was a Thursday.
January 31, 1892, was a Sunday.
It was a Wednesday.
Jan 31st
The day of the week was Thursday, if that is what you are asking.
December 31st, 1973 fell on a Monday.
August 31st 1997 was a Sunday.
31st March 1957 was a Sunday.
31st March 1851, was a Monday.
31st October 1967 was a Tuesday.
July 31st 1958 was a Thursday.