The best time to go to Glendalough is during the shoulder seasons of spring (April to May) and autumn (September to October), or during the summer months (June to August) for the warmest weather.Spring is a wonderful time to visit, as the landscape bursts into colour with wildflowers and the weather is generally mild, making it pleasant for walking and exploring the monastic site. You'll find fewer crowds compared to the peak summer months, allowing for a more tranquil experience of the valley's natural beauty and historical sites.For those who prefer warmer temperatures and longer daylight hours, summer offers the best conditions for outdoor activities like hiking the various trails around the Upper and Lower Lakes. While it's the busiest time, the extended daylight means you can enjoy the stunning scenery well into the evening. Families with children often find summer ideal for their holidays, as there are plenty of opportunities for outdoor adventure and picnics by the lakes.Autumn provides a spectacular display of changing foliage, with the surrounding Wicklow Mountains turning golden and russet. The air is crisp, and the trails are often less crowded than in summer.