When to go
Berlin is in a temperate climate zone so the general weather is quite pleasant all through the year. There are four distinct seasons. Temperatures don’t have too large a range between the extremes; -1°C in the winter (December-February) up to around 25°C in the summer (June-August). Needless to say, if you do not enjoy the cold, do not travel in winter, and if you do, remember to take enough warm clothing.
The tourist season is from May to October but there are attractions and festivals all through the year. Check beforehand to see which ones you will be able to witness. Being the arts and music hub of Germany, there will definitely be several concerts, plays and exhibitions on play during your trip for you to take advantage of.