Answered my own question and will post for anyone who has the same issue. datevec extracts the month and day. Example:
t=datevec(TIMESTAMP)
55004 10 29 0 0 0
55004 10 30 0 0 0
55004 10 31 0 0 0
55004 11 1 0 0 0
55004 11 2 0 0 0
Then just reference specific columns of t. As in:
Month=t(:, 2);