Hey dear Berliners!

I am moving to Berlin for a short term assignment this autumn and will sat till mid october. I was to be in Frankfurt but they changed the location to Berlin. I am looking forward to trying the Octoberfest and enjoy autumn before things get too cold.

1) what's weather like in September? Would I need my trench coats and sweaters?

2) I am planning on doing some weekend trips to Hamburg and over the border to Poland. Would you have other suggestions that you thoroughly enjoyed?

3) any tips for food to try or places to visit , I am all ears!

Thanks again!

Edit: when I said oktoberfest, I only meant the Oktoberfest parties where I could probably get to try beer which I otherwise wouldn't have discovered. Fully aware that Munich is the beer daddy and it's far away from Berlin!