The present study shows an analysis of how the atmosphere affects the thunderstorm formation in Medellin City (Colombia). To carry out this study a meteorological station located in Olaya Herrera Airport and a LINET Lightning Locating System network were used. To understand the atmosphere role, atmospheric pressure, near surface air temperature, dew point temperature and wind measurements are used. Results show that more than 60% of total lightning are present during the periods of March-April-May and September-October-November. This study ratify that Medellin is a city with one of the highest lightning activity in the world with 202 thunderstorm days in average. Additionally, the diurnal cycle of lightning activity shows that for all the analyzed periods more than 50% of lightning detected are present between 11:00 and 17:00 hours in local time.