Just noticed this. Berlin has consistently been the last weekend of September. I was expecting September 30, 2018. The official website says the 2018 race is September 16. Granted it's really only a week earlier than this year, but still... in light of recent weather trends everywhere, you'd think they'd want two weeks later rather than mid-September?
https://www.bmw-berlin-marathon.com/m/en/plan-your-race/registration-2018.html