Dublin in October

May through September gives you the best shot at decent weather, though 'decent' in Dublin means it might not rain for a few hours straight. July and August are warmest but also when every other tourist shows up – expect crowds at Trinity College's Book of Kells and long waits at popular restaurants. June and September hit the sweet spot with fewer crowds and weather that's actually pleasant for walking around. The city stays lively year-round thanks to the pub culture, but winter days are short and grey. St. Patrick's Day in March is obvious but overrated – the locals mostly avoid Temple Bar and let the tourists have it. Summer brings festival season, with events like the Dublin Theatre Festival and Longitude music festival. Spring arrives late, usually not until April, but when it does, the city's many parks come alive. Pack layers regardless of when you visit – Dublin weather changes faster than a conversation in a pub.