Wikipedia:
The date of the feast is occasionally moved by church authorities when March 17 falls during Holy Week; this happened in 1940 when Saint Patrick's Day was observed on April 3 in order to avoid it coinciding with Palm Sunday, and happened again in 2008, having been observed on 15 March.
I thought it was today.
Oh well. Get drunk and be Irish. And if you already did, do it again!
