Geography of Dehradun District mainly includes highland areas having cooler temperatures and vast forests. Topographically, the region can be divided into two distinct tracts namely the montane tract and the sub-montane tract. The montane tract covers the entire Chakrata tehsil of the district and consists entirely of a succession of mountains and gorges and comprises Jaunsar-Bawar. The mountains are very rough with steep slopes. The most important features of the tract are the ridge which separates the drainage areas of Tons River on the west from that of Yamuna Riveron the east. Below the montane tract follows the sub-montane tract, which is the famous Dun valley bounded by Shivalik hills in the south and outer scarp of Himalaya Mountains in the north.
The climate of Dehradun District is generally temperate. It varies greatly from tropical to severe cold depending upon the altitude of the area. The district being hilly, temperature variations due to difference in elevation are considerable. In the hilly regions, the summer is pleasant, but in the summer season, the heat is often intense, although not to such degree as in the plains of the adjoining district. The temperature drops below freezing point during the winters, when the higher peaks are also under snow. The area receives an average annual rainfall of 2073.3 mm. Most of the annual rainfall in the district is received during the months from June to September, July and August being rainiest
Geography of Dehradun District is distinguished from most of the other districts in the state by the existence of very large forests chiefly stocked with Sal. Forest products play an important role in the economy of the district. Besides, supplying fuel, fodder, bamboos and medicinal herbs, they also yield a variety of products like honey, gum, catechu, wax, horns and hides. The forest area of Dehradun District account for near about 1477 sq kms of area, around 43.70 percent of the total area of the district. Owing to the variation in altitudes and other aspects, the flora of the district varies from tropical to alpine species. Different types of forests and varying species of shrubs, climbing plants and grasses, depending upon the aspect, altitude and soil condition are found in Dehradun District. Sal forest and coniferous forests are predominant in the western part of the district. In the eastern part of Dehradun District, the forests may be divided into a number of Botanical divisions that are mainly Moist Shivalik Sal Forests (low quality of Sal is found in these forests), Moist Bhabar Doon Sal Forests, West Gangetic Moist Deciduous Forests, and Dry Shivalik Sal Forests (these forests are found on the higher slopes of Shivalik hills. In Chakrata tehsil they occur near the junction of the Tons and the Yamuna rivers. Sal is the predominant species found in these forests). Besides these, many other types of forests occur in small belts in the plain of the district.
Geography of Dehradun District also includes several major rivers, canals and waterways. The Shivalik range (outer and lower ranges of Himalayas) lies at its feet, the outer scrap of the Himalayas bound it on the north and the scared Ganga River and the Yamuna skirt in on the east and the west respectively. Ganga enters Dehradun District in the eastern part and meandering south-west goes to Haridwar via Raiwala village near Rishikesh. Yamuna enters the district in Jaunsar and flows southwards for about 32 kms on the south-east border of the district. Besides, Ganga and Yamuna, the other rivers that flow through Dehradun District are Asan, Suswa, Tons, Rispana, Bindal and Amalava.