The Faroe Islands have no bad season, but the reasons to visit Sørvágur change dramatically through the year.
Summer (June–August) is the peak for most visitors. The Mykines ferry runs daily, the puffins are nesting, the days are extraordinarily long (near-midnight twilight in June), and the hiking trails are at their most accessible. The downside is that this is also when Vágar is busiest — the Sørvágsvatn trail and Mykines ferry fill up, and accommodation needs booking well ahead. The weather is mild but rarely warm; expect temperatures of 10–15°C and pack for wind and rain regardless of the forecast.
Spring (April–May) and autumn (September–October) offer a reasonable balance: fewer visitors, the lake trail still walkable, and a good chance of the dramatic low-angle light that makes Faroese landscapes look their most spectacular. The Mykines ferry typically starts in late April or May and ends in September.
Winter (November–March) closes the ferry to Mykines and shortens the days to a handful of hours, but the islands take on a different kind of appeal — austere, atmospheric, and very quiet. The airport operates year-round, and the road to Bøur and Gásadalur is accessible in all but the worst weather.