When to go to germany and weather of germany

Any time is good to visit Germany, but almost everyone prefers between May and September, when it is more likely to have warm weather and sunny skies.

--> Much of life goes outdoors: the breweries and outdoor cafes are in full swing, festivals and outdoor events enliven towns and cities. It is also the best time for hiking, biking, water sports and other outdoor activities. The downside is that traffic increases, the accommodation is expensive and scarce, and castles, themeparks and other attractions are crowded.
The months of March to May and October attracts few tourists, often surprise with good time and show a range of colors: spring wildflowers and flowering trees, and autumn leaves fall.
 
Without winter sports, activities that can be done between November and early March are usually reduced to cultural and urban spectrum. Museums and other attractions reduce their opening hours or close. Some smaller accommodations, especially in rural areas, close all of November to early December, when they re-open. The ski season usually starts in early to mid December, reaches its peak on New Years Eve and extends until March or so.
http://howto102.blogspot.com/2013/05/top-10-best-places-to-visit-in-austria.html