Festivals!
Festivals in Guild Wars 2 are yearly recurring events that typically last for 3 weeks. Each festival has it's own activities, lore, rewards and achievements.
Their exact start date changes from year to year, so I've just given general start ranges.
Lunar New Year
Starts mid January to early February
Super Adventure Box
Starts late March to mid April
Dragon Bash
Starts in early to late June.
Festival of Four Winds: Labyrinthine Cliffs
Starts late July to August
Festival of Four Winds: The Crown Pavilion
Starts late July to August
Halloween
Starts mid October
Wintersday
Starts mid December
