Today, half of the World population lives in cities. The international network of meteorological offices is only 150 years old, but knowledge about urban climate is very scant and communication on this topic has been standardized by the media.Urban air quality is improving with technical progress and economic development but vulnerability is still very high. Meteorological hazards lead to crisis, causing damages which are compensated at a very high cost. Since there is no universal climatic urban model, and since a unique artificial climate cannot isolate cities from climatic hazards, each one has to innovate for its own.