precipitation (mm) and wind velocity (m/s). Readings from these meteorological conditions were obtained for the day of the event, the previous day, and mean results for 3 days, 1 week and 1 month prior to the event. The moon phase for every day and seasonality were also determined. 75 controls per case were randomly selected in a one-year period before and after every event, in the same meteorological station, for every rupture, and compared. Comparisons of all these variables between ruptures and controls were performed. Results: A total of 717 with rAAA were identified, and 53775 controls were randomly selected. There were significant low temperatures, low solar global irradiation and higher mean humidity levels in all analyzed time periods (from the same day to one month before) when rAAA occurred (P< 0.001, < 0.001 and < 0.05, respectively). Variability of atmospheric pressure 7 days and 1 month before the event also showed an increment on AAA rupture risk (P¼0.01 and P¼0.005). According to seasonality, the majority of rAAAs occurred during fall and winter (56.9%, P< 0.001). All the prognostic variables were more frequent in fall-winter, but logistic regression did not identify a clear independent prognostic factor. In regard to lunar phases, the frequency of AAA rupture was significantly higher during the waning moon period (27.9%) versus the other periods (P¼0.035). Conclusion: This study shows that the incidence of rAAA is higher during fall and winter. Meteorological factors such as temperature, global solar irradiation, humidity and variability of atmospheric pressure on previous days (up to one month before rupture), increase the risk of AAA rupture. Finally, we observed that rAAAs occur more frequently on periods of waning moon, although the pathophysiologic mechanisms are still unknown.