Germany's high travel season is in the summer, particularly from June until September. For cheap flight and less crowds, consider visiting Germany during the shoulder period between winter and summer, typically April and May or September and October.
Spring is the time for Fashching, Germany's equivalent to Mardi Gras. It's also known as the fifth and foolish season. Major celebrations occur in Munich, Cologne and Mainz; visitors are likely to see huge parades, masked balls and other festivities.
If you are a wine connoisseur, consider visiting Germany during the months of August and early September when many of the local wine festivals take place such as the famous Stuttgart Wine Festival or the Rudesheim Wine Festival.
Visitors hoping to enjoy Oktoberfest should be sure to visit Munich during the end of September or early October. In addition to the famous beer tents, visitors are treated to roller coaster rides, food and traditional Bavarian music.
Christmas is an excellent time to visit Germany in order to experience the seasonal markets found throughout the country. The market times vary from town to town, but generally visitors can find Christmas markets from late November all the way up until December 24. Dortmund Christmas Market features 300 stalls and a 45-meter tall tree.