Fredrikstad is at its best from late May through August. The Old Town hosts markets, outdoor concerts, and the International Animation Festival (FREDAFF) in late summer. The Glomma river fills with small boats, the Oslofjord beaches are swimmable, and the fortress ramparts are busy with visitors. Winter is quiet and cold, though the fortress has a particular beauty under snow if you can handle the short days.
The Fredericia Art Museum — housed in a restored factory — runs year-round, as do the small craft galleries in Gamlebyen. Frederikstad Motorfestival in May draws classic car enthusiasts and adds a layer of activity to the spring shoulder season.