It comes in at 66 and cheats by using a module... but it was really just so I could take Time::Piece for a spin... I *really* like it! Perhaps this snippet doesn't highlight its strong points, but you should take a look at it. I will probably be cutting way down on my Date::Manip/Date::Calc/Time::Local/POSIX::strftime usage, in favor of Time::Piece.

sub f{
#234567890#234567890#234567890#234567890#234567890#234567890#23456
use Time'Piece;(Time'Piece->strptime("25Dec".pop,"%d%b%Y"))->_wday
}
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-Blake