Lufthansa has announced that it has cancelled all flights to between from Munich or Frankfurt to Berlin for Monday, March 13, 2017. This as a result of a strike announcement by Ver.di who represents Ground Workers at both Berlin airports (Tegel and Schonefeld).
The strike scheduled for tomorrow comes on the heels of a walkout last Friday, and also comes conveniently during the ITB travel show taking place in Berlin at the same time. Plans call for upwards of 2000 workers to walk off the job at 4:00a Monday through 5:00a Tuesday, making for a 25 hour strike.
If your plans included transiting Berlin tomorrow please use this link to see what your options may be. Typically you can rebook to travel on a different day for no charge, get a refund, or switch to a Deutsche Bahn train ticket to get you to your destination.