By Rick Steves
Spring and fall offer the best combination of good weather, long days, and plenty of tourist and cultural activities — particularly during Holy Week, Lisbon's series of June festivals (which peak on St. Anthony's Day, June 13), and Porto's celebrations of St. John's Day (June 23–24). If you want to attend one of the major pilgrimages to Fátima, plan to be there on either May 13 or October 13. While crowds are generally light in Portugal in spring and fall, book accommodations well ahead if you'll be visiting a spot during any big-time event.
Summer months are the most crowded and expensive in the coastal areas. Beach towns (such as Nazaré or along the Algarve) are packed with vacationers in July and especially in August — when rates go sky-high and it can be tough to find a room. Those same towns are a delight in shoulder season (mid-May–June and September–mid-October), when the weather is nearly as good and the crowds subside — but they can be dreary and pretty lifeless in the winter. While Portugal is not nearly as hot as Spain (except in the Alentejo region), an air-conditioned room is worth it in summer.
In the off-season (roughly November–March), expect shorter hours, more lunchtime breaks at sights, and fewer activities — with the big exceptions of Christmas festivities and Entrudo (carnival), which is especially raucous in Lisbon and a few towns in the Algarve.