... City centre local 7b to 8a. But only the city centre is 7b-8a, the suburbs , oficial weather station at the airport (radius 30km) is 7a and the hills to Czech Rep. are Zone 6a-b. Our absolute Min in City Centre was -13,1°C in 1985. At the airport -25°C 1985!
In Southern Germany you find 8a (Rhine region) to Zone 5a (Alps and some dales in Bayer. wald).
Greets