Rise in Average Summer Temperatures (in Celsius) (2071-2100 as compared to 1971-2000): According to the MPI-M scenario, summers in southern Germany in the last three decades of the 21st century will be about 3 degrees warmer than they have been in recent decades. In the north, they will increase by two degrees. If you believe this report, you might want to think about timing your purchase of a vacation home on the North Sea or Baltic Sea. It might mean better weather, warmer water and higher increases in property values.