Introduction. There is very little literature data on the correlation between the seasons, temperature and atmospheric pressure, and pathogenesis of acute appendicitis (AA). Objective. The aim of this research is to investigate the association between the seasons, changes in atmospheric temperature and pressure, and patients’ age and severity of the clinical form of AA in the city of Niš. Methods. This study included 395 patients diagnosed with AA, who, during the two-year period, from July 1st 2011 to June 30th 2013, were hospitalized and operated on at the Department of General Surgery, Clinical Center in Niš, Serbia. Results. The increased average daily values of barometric pressure by 1 millibar on the day when the event took place was associated (p < 0.05) with the decrease of total risk of the occurrence of appendicitis by 2.2% (0.2-4.1%). In all observed patients, each increase of the mean daily temperature by 1°C three days before the event took place (Lag 3) was associated (p < 0.05) with the increase of total risk of the occurrence of appendicitis by 1.3% (0.1-2.5%). Conclusion. According to the results of this research, we can conclude that patients’ sex, age and severity of the clinical form of AA are not in connection with the seasons, while there are certain connections between appendicitis occurrence and atmospheric temperature and pressure.