The present investigation was carried out at Mallawy Agricultural Research Station, El-Minia Governorate, Egypt during the two successive seasons; 2010/ 2011 and 2011/2012. The objective of this investigation was to study the effect of sowing dates expressed in the accumulated temperature on yield and its components of three durum wheat genotypes (Triticum durum), i.e., Beni sweif-1, Beni sweif-4 and Beni sweif-5 in three sowing dates, namely; 21st November, 10th December and 30th December during the two winter growing seasons. The studied characteristics included plant height, and number of spikes/m², number of kernels/spike, 1000-kernel weight, grain yield, straw yield and grain filling period. The results showed that all the sowing dates and cultivars reached to maturity at 140.2 days after sowing (DAS) (1652.2 °C days) in season 1 and at 152.4 DAS (2016.4 °C days) in season 2. Heading date and anthesis were significantly affected by cultivars and sowing dates in both growing seasons, also the interaction in the second season. Days to maturity were significantly affected by sowing dates in the two growing seasons and cultivars in the first season . Plant height was significantly affected by cultivars and sowing dates in both growing seasons; also significant interaction was observed between cultivars and sowing dates in the second season only. Number of spikes/m² was significantly affected by sowing dates in both growing seasons; also cultivars in the second season on spike/m2. Number of kernels/spike and thousand kernel weight were significantly affected by cultivars, sowing dates and the interaction between cultivars and sowing dates in the second season only. Grain yield/plot was significantly affected by sowing dates in both growing seasons and cultivars in the second season. Straw yield was significantly affected by sowing dates in both growing seasons because the sowing dates (thermal time) was the main limiting factor to straw and grain yield in two growing seasons 2010/2011 and 2011/2012. Grain filling period was significantly affected by sowing date in both growing seasons and the interaction cultivar × sowing date was significant in the second season. The current study showed that the first sowing date was the optimum date for Beni sweif-1 in both growing seasons. These results are discussed in relation to future improvement of yield in respect to the variation of meteorological data in winter season with a spot light on thermal time.