The Merrie Monarch Festival
begins on the first Sunday after the first full moon after the Spring equinox. (next Sunday)
Euge is correct, this is also when Easter occurs. This year is significant because it is almost as late as Easter can ever be in the year. The last full moon (remember the perigee full moon?) occured just 28 hours prior to equinox, and the first full moon after the equinox occured on a Sunday. So, it is possible for Easter to only be one day later in the year than it is this year (this is why Mardi Gras was so late this year too).
Be that as it may, the full moon tonight, here in the last time zone, is amazingly beautiful - beauty full.