This paper presents a innovative system for weather monitoring using one device called WeBo, equipped with weather sensors and GPS, placed on buses ceiling to measure weather variables like humidity, temperature and air quality during the bus path. The weather variables are stored together with the latitude and longitude of the measure place and the exact time of measurement. WeBo synchronize its data with all other WeBos met during the path due a Bluetooth radio. This same radio is used to upload the data when the bus arrives in the terminal to a server called TeCo. The data downloaded by TeCo is transmitted to a main server and processed by a system called SysCo. With the information captured by the buses during the day, SysCo can generate reports of points in the city where the temperature is above the normal, and places where the air quality is inappropriate.