Vänersborg is a place for summer. The lake-shore setting comes into its own from June to August, when the water is warm enough to swim in, the evenings are long, and Halleberg and Hunneberg are at their most welcoming for walking. The town fills with Swedish summer visitors in July, but it never reaches the intensity of the coastal resorts.
Spring (April–May) is pleasant for walking the table mountains — the forest is still open and the elk are easier to spot before the summer foliage thickens. Autumn brings excellent birdwatching on the lake margins, with large gatherings of migratory wildfowl. Winter is quiet, cold, and grey; unless you are specifically interested in cross-country skiing on the plateaus, there is little reason to visit between November and March.
The Birger Sjöberg Days festival in late May is the main local cultural event, with music, readings, and street performances across the town.