Guatemala is a place where activities occur all year long. Most of them have a religious motive. You can check or event calendar here. Some of them are:

New Year’s Day January 1st
Semana Santa from Holy Wednesday midday thru Easter (officially Thursday and Friday)
International Work Day May 1st
Armed Forces Day June 30th
Assumption DayAugust 15th (Guatemala City only)
Independece Day September 15th
Revolution Day October 20th
All Saint’s Day November 1st
Christmas Eve December 24th
Christmas December 25th
New Year’s Eve December 31st

Local holidays on Patron Day varies each city.