Kőszeg is pleasant in any season but at its best from late spring through early autumn. May and June bring mild weather and lush forests in the Kőszeg Mountains without summer crowds. July and August are warm and busy, though "busy" is relative — this is a small town and never feels overwhelmed. The wine harvest in September and October is a good time to visit if you want to taste local Kékfrankos straight from the barrel at the cellars around town.
The most atmospheric time to visit is around 30 August, when the town celebrates the anniversary of the 1532 siege with historical re-enactments, costumed parades, and events in the castle courtyard. The daily 11am bell-ringing, which commemorates the moment the Ottomans withdrew, is worth timing your morning around year-round.
Winters are quiet and cold. Most of the mountain trails are walkable but the town takes on a sleepy quality that some visitors find appealing and others find dull. The forested hills above Kőszeg are popular with cross-country skiers after snowfall.