Climate is one of the most important geographical factors in defensive and military affairs which should always be taken into consideration by designers in the defensive and military fields in choosing doctrines, tactics, and even in choosing the type of military forces, clothes, logistics, maintenance and installations. A challenge for strategic commanders in long term planning is knowledge of climatic calendar of various zones. In the present research, for zoning and evaluation of climatic conditions of Sistan and Baluchestan Province in terms of military operations, all synoptic stations of the region were studied. From among them, seven stations which had a statistical period of higher than 30 years were chosen. The climatic data regarding temperature, relative moisture, speed and direction of the wind, cloudiness, vision field, daily and monthly rainfall and snowfall were taken from the organization of meteorology. Then, the threshold of effective climatic elements in military operations were identified, and the probabilities of effective parameters on military operations were calculated. In addition, using physiologic equivalent temperature, climatic welfare and effective cold and warm tensions on military forces during various months were evaluated. Furthermore, based on the indicator of military climate, the condition of the region was studied for its climatic desirability for various military operations during year. The findings revealed that the level of desirability of south east region of Iran in terms of military climate was low during warm and summer season, and it was high during cold and moderate season of the year. The least level of climatic desirability for military operations was found to be in Tir and Mordad. Furthermore, form among the stations in this province, the least desirable stations for military operations were found to be Zabol and Zahak which are affected by 120-day wind storms of Sistan. On the opposite, the highest desirability for military climate was found to be in Aban, Mehr and Esfand, and the stations of Chabahr, and Saravan enjoyed the most desirable defensive climate during these months.