One of Southwest Ireland's most attractive locales, Killarney is also the most heavily visited town in the region (its proximity to the Ring of Kerry and to Shannon Airport helps to ensure this).
Killarney is famous for its lakes, not for the town, a point to bear in mind in order to avoid disappointment. Killarney town was one of the first places in Europe to owe its existence almost entirely to the tourism industry. Visitors started seeking out the region’s dramatic lake scenery in the early 19th century, and the arrival of the railroad ensured its growing popularity. Today Killarney is a small, low-key town lined with shops and eateries firmly targeted at the numerous visitors, but it’s also a popular holiday destination for Irish visitors, and retains the traditional friendliness of less famous towns. There’s a lively restaurant scene, and some good crafts and clothing shops, but you may want to limit time spent there if discos, Irish cabarets, and singing pubs—the last of a local specialty with a strong Irish-American flavor—aren't your thing.
The nightlife is at its liveliest from May to September; the Irish and Europeans pack the town in July and August. Peak season for Americans follows in September and October. At other times, particularly from November to mid-March, when many of the hotels are closed, the town is quiet to the point of being eerie. Given the choice, go to Killarney in April, May, or early October.
Light rain is typical of the area, but because of the topography, it seldom lasts long. And the clouds' approach over the lakes and the subsequent showers can actually add to the scenery. The rain is often followed within minutes by brilliant sunshine and, yes, even a rainbow.