Physical Geography of Assam is extremely interesting with its geologic origin, geomorphic characteristics, climate, rich biodiversity, etc. Assam, extending from 89 degree 42 minutes E longitude to 96 degree E longitude and 24 degree 8 minutes N latitudes to 28 degree 2 minutes N latitudes in the graticule is a North Eastern state of India. Assam is located at the central part of the North-East India and with an area of 78,438 km² it is almost equivalent to the size of Ireland or Austria.

Assam is in the eastern most projection of the Indian Plate, where it is thrusting underneath the Eurasian Plate creating a subduction zone. It is postulated that due to the northeasterly movement of the Indian plate, the sediment layers of an ancient geocyncline called Tethys (in between Indian and Eurasian Plates) have been pushed upward to form the Himalayas. It is estimated that the height of the Himalayas is increasing by 4 cm each year.

Therefore, Assam possesses a unique geomorphic environment, with plain areas, dissected hills of the South Indian Plateau system and with the Himalayas all around its north, north-east and east.

Geomorphic studies also conclude that the Brahmaputra is a paleo-river, older than the Himalayas, which often crosses higher altitudes in the Himalayas eroding at a greater pace than the increase in the height of the mountain range to sustain its flow.

The height of the surrounding regions still increasing forming steep gorges in Arunachal.

Entering Assam, the Brahmaputra becomes a braided river and along with its tributaries, creates the flood plain of the Brahmaputra Valley. The Brahmaputra Valley in Assam is approximately 80 to 100 km wide and almost 1000 km long and the width of the river itself is 16 km at many places within the valley.

The hills of Karbi Anglong and North Cachar and those in and around Guwahati and North Guwahati (along with the Khasi and Garo Hills) are originally parts of the South Indian Plateau system.

These are eroded and dissected by the numerous rivers in the region. Average height of these hills in Assam varies from 300 to 400mt.

The southern Barak Valley is separated by the Karbi Anglong and North Cachar Hills from the Brahmaputra Valley in Assam. The Barak originates from the Barail Range in the border areas of Assam, Nagaland and Manipur and flowing through the district of Cachar, it confluences with the Brahmaputra in Bangladesh.

Barak Valley in Assam is a small valley with an average width and length of approximately 40 to 50 km.

With the 'Tropical Monsoon Rainforest Climate', Assam is a temperate region and experiences heavy rainfall and humidity. Winter lasts from late October to late February. The minimum temperature is 6 to 8 degrees Celsius. Nights and early mornings are foggy, and rain is scanty. Summer starts in mid May, accompanied by high humidity and rainfall.

The maximum temperature is 35 to 38 degrees Celsius, but the frequent rain reduces this. The peak of the monsoons is during June. Thunderstorms known as Bordoicila are frequent during the afternoons. Spring and Autumn with moderate temperatures and modest rainfall are the most comfortable seasons.