The “Smart” concept applied to the cities intends to improve different fields of the urban context and in particular the life quality of citizens. An important part of the overall well-being is the urban comfort, defined as a function of some environmental parameters. The knowledge and the widespread collection of the geospatial information allow the implementation of a model able to estimate the urban comfort level. In this respect, a dynamic monitoring system was developed following the Do It Yourself (DIY) approach that allow to collect and send data to a cloud server. The article describes the implementation phases of the device and a first experimental application conducted in Milan.