Joensuu has two strong seasons: summer (June–August) and winter (December–March). The choice depends on what you are after.
Summer is the main season: long days, the Pielisjoki river walkable and pleasant, Koli accessible, Botania's outdoor gardens at their best, and the Ilosaarirock festival in July drawing visitors from across Finland. Midsummer is celebrated with particular enthusiasm in Finnish lake country — bonfires on the shores, boats on the water.
Winter is cold and dark — temperatures regularly fall below –20°C — but the snow transforms the landscape and cross-country skiing from Joensuu is excellent. Koli has downhill skiing. The aurora borealis can sometimes be seen from the region in clear nights from October to March. Botania's tropical greenhouse is especially welcome in winter — the contrast between the frost outside and the butterflies inside is memorable.
Spring and autumn are transitional seasons, with spring bringing dramatic snowmelt and the ice breaking up on the lakes, and autumn bringing the colour of birch and aspen. Autumn is also mushroom and berry season, when Finns disappear into the forest.