Arouca works in every season, but the experience varies considerably depending on when you arrive. The Passadiços do Paiva trail and the 516 bridge are open year-round, though winter rain makes the wooden boardwalks slippery and the gorge can be dramatic and wild rather than inviting.
Spring (April–June) is the best time for the trails: the river is full, the hillsides green, temperatures comfortable for walking. The crowds are manageable compared to summer, and the waterfalls on the Serra da Freita are at their most powerful.
Summer (July–August) is peak season. The bridge and trail are busy, parking fills early, and advance booking for the 516 is essentially mandatory on weekends. The gorge provides shade, so the trail remains walkable even in heat, and the river pools are a welcome reward. Expect company.
Autumn (September–October) rivals spring for conditions. The light is better, the colours are changing, and the summer crowds have thinned. This is arguably the nicest time to visit.
Winter is quiet and the landscape can be beautiful when the Serra da Freita is dusted with snow. The town is empty of tourists; the monastery and geopark centre are open. The bridge is open but conditions can be wet and cold. Worth considering if you prefer solitude.
The Arouca pilgrimage to Blessed Mafalda takes place in late May, drawing local visitors to the monastery.