Pi is an irrational number, so I guess its to be expected that various individuals would assume that 3.141592653 represents March 14, but only in America, where we put the numerical month ahead of the numerical day, very irrationally since it makes more sense to begin with the day, then the month, then the year in ascending order. This is like the millennium year error all over again.
Pi day - as celebrated everywhere else on the rest of the planet - is obviously correctly determined as 31 April, 2015 at 9:26:53 AM.
Whats that you say? April has only 30 days? There is no April 31?
Well, then what could be more irrational than that? Heres to Pi Day, April 31, 2015 at 9:26:53AM!
In Japan it will be celebrated on 2031 April 15. :-)