Sellee Beach offers safe swimming conditions during summer months, with sandy bottom and gradual depth suitable for most swimmers. Located in the northern Bothnian Bay, water temperatures remain quite cool, typically 14-17°C even in July and August, so tolerance for cold water is necessary. No lifeguard services are typically available at this local beach, requiring swimmers to be self-sufficient and cautious. Water quality is generally good in this less developed area. Families should supervise children closely. The beach's location outside the main city center means fewer amenities but also quieter, more natural conditions.

The best weather for Sellee Beach occurs from late June through early August when temperatures are warmest and the midnight sun provides extraordinary extended daylight. July typically offers peak conditions for swimming, though water remains cold by international standards. The beach's hidden nature means crowds are never significant, but summer weekends see more local visitors. For complete solitude, visit weekday mornings or evenings. Early June and late August provide beautiful scenery with fewer people but cooler conditions. The area's far northern location means dramatic seasonal variations, with summer being the only practical beach season.