December in Słupsk averages a daily high of 3.8°C with nights around -0.9°C. Expect roughly 16.9 wet days totalling 50.9mm. A hard month to visit for comfort alone.
Across the year, the best time to visit Słupsk is June–August.
Based on LEBA, PL (45.5km), 1995–2024. 21 years of December data.