The Mediterranean fruit fly (MFF), Ceratitis capitata (Wied.) (Diptera: Tephritidae) is an important economic pest worldwide. The present work aimed to study the effect of peach fruit ripening and certain weather factors on population fluctuations of MFF on peach orchards during two successive seasons (2015 and 2016). An area of about 25 feddans was selected for the present study at Aga district, El-Dakahlia governorate, Egypt. The MFF showed two peaks of seasonal activity at the period of fruit ripening during the first season, whereas it recorded four peaks of abundance during the second season. Generally, these peaks of activity were confined between June and September. Population of MFF positively responded to fruit ripening. Among the weather factors, temperature has the highest effect on MFF population; relative humidity has the lowest, and wind speed has a moderate effect. The MFF population responded positively to both temperature and humidity, whereas it responded inversely to wind speed. Although weather factors had effects on MFF population, fruit ripening exhibited an extrusive effect on its population. Updating the information regarding factors that affect population dynamics of an insect under various ecological situations might lead to provide insights into pest control.