Walpurgis night is celebrated with bonfires all around the country on the last day in April. The day after (1st May) is a public holiday.
Sweden's national day, also called "flag day", is on 6th June.
In the end of August the Surströmmning season starts. This is a Swedish delicacy fish that smells awful, some swedes hate it, some swedes love it. You should try!
4th of October is dedicated to Sweden's famous cinnamon buns (kanelbullar).
As in most parts of the world, on the last day of October we celebrate Halloween.
A famous event with a parade through the city celebrated on 13th December.