Lisbon has long warm summers, pleasant warm autumns and mild winters. The peak of the tourist season is from June to the end of September, while the beaches are the busiest in July and August. The weather is suitable for spending time on the beaches of Lisbon from May to mid-September.
The best season to visit Lisbon is late spring or early autumn, when there are fewer tourists, but the weather is still beautiful. A good time of year to visit Lisbon is during the Festas Santos Populares (June), when the city has a festival atmosphere.