Silves is at its most pleasant in spring (March to May) and autumn (September to October), when temperatures are warm but not oppressive and the almond and orange blossoms or harvests add colour to the surrounding countryside. Summer (July and August) is hot — regularly above 35°C — and while the interior of the castle and museum provide shade, the walk up from the car park to the castle walls can be exhausting in the afternoon heat.
The Medieval Fair in August is a major event that transforms the town for a week or more, with costumed traders, jousting, period food, and evening entertainments. It is very well done but the town fills up completely; book accommodation well in advance if you want to attend.
Winter is mild and quiet, occasionally wet. The town is uncrowded and the sites are easily accessible, though some cafés reduce their hours. A good time for anyone who wants the place to themselves.