Due to the fare war between United and American where United has been targeting some of AA’s Hubs, LH passengers get to benefit from the fare deals. This happens because the agreement between LH and United is that United sets the fares for Star Alliance member flights departing the USA, so basically what United charges as a fare, will be the same on Lufthansa, SWISS, Austrian, Brussels, and Air Canada.
Though there are a lot of great deals, especially on Tuesday departures in November and December, Philadelphia – Dublin is hands down the best deal with fares ranging between $290 and $320 (yes, roundtrip). Other deals out of Miami, Dallas, St. Louis, and Phoenix are good, but not as good as PHL – DUB. The absolute lowest prices seem to happen in November.
Book quick, fare wars are unpredictable and can end anytime without notice.