Lisbon has one of Europe's finest climates — 290 days of sunshine per year. Winters (December–February) are mild and rainy at 12–16°C — still very pleasant for a city break. Spring (March–May) is beautiful: wildflowers, mild temperatures (16–22°C), and the city waking up. Summer (June–September) is warm and dry at 26–30°C with Atlantic breezes.
October remains warm (20–24°C) and is arguably the best month to visit: summer crowds thin, prices drop, and the light is golden. July–August is peak season — very crowded at Jerónimos and Sintra. The Festas de Lisboa in June (particularly June 12-13 for Saint Anthony) sees sardine grills set up on every street and the city celebrating joyfully.