The province of Tehran has over 12 million inhabitants and is Iran's most densely populated region. Approximately 84.15% reside in urban areas and 15.85% in rural areas of the province.

The highest point of the province is Mount Damavand at an elevation of 5,678 m, and the lowest point of the province being the plains of Varamin, 790 m above sea level.

The largest Lakes of this province are Karaj River and Jajrud River.

Mountain ranges such as the Alborz span the north; Savad Kooh and Firooz Kooh are located in the north east; Lavasanat, Qarah Daq, Shemiranat, Hassan Abad and Namak Mountains are in the southern areas; Bibi Shahr Banoo and Alqadr are situated in the south east and the heights of Qasr-e-Firoozeh being located to the east of the province.

Environmentally speaking, the climate of Tehran province in the southern areas is moderately warm, but in the mountain vicinity it is cold, and in the higher regions it is even colder with long winters and fairly large amounts of snow. The hottest months of the year are from mid-July to mid-September when temperatures range from 28°C to 30°C, and the coldest months experience -10°C around December–January. Tehran city has cold winters and hot summers. Average annual rainfall is approximately 500 mm, the maximum being during the winter season.