Oulu has a strong summer and a strong winter, with little in between. Summers (June–August) are short, often sunny, and the days are extraordinarily long: in late June, the sun barely sets. The Air Guitar World Championships fill the city in late August.
Winter runs November through March, with frozen sea, snow-covered islands, and reliable cross-country skiing from the city centre. Autumn (September–October) is short, rainy, and dark. Spring (April–May) is the worst time — slushy, grey, and unflattering.