Late summer and early autumn (September and October) is the best time to visit Monterrei. The vineyards are in full leaf, harvest is underway, and the wine bodegas are most accessible for visits and tastings. The weather in the valley is warmer and sunnier than the Galician coast — Monterrei sits in a rain shadow created by the mountains to the west, and summer temperatures regularly exceed 30°C.
Spring (April–May) is also pleasant, when the valley is green and the wildflowers are out. The famous Entroido de Verín carnival takes place in February or March (the dates shift with the Catholic calendar) — one of the most spectacular carnival traditions in Galicia. Winter is quiet, cool, and often misty in the valley, but the castle is never crowded and the spa hotels offer good off-season rates.