The physiographical regions of Tirap district are as follows - Namchik-Tirap River Valley: It is a shared valley of Tirap and Namchik rivers, both of which have their source at the top of Patkai Hills or Purvanchal Ranges. The region covers an area of near about 1300 sq. kms. It basically spreads over the Lazu circle and also in some parts of Khonsa circle of Tirap District, and the rest of it is covering Changlang District. The region is bounded by Tirap River and Assam in the North, Myanmar in the south and Namsang and Wakka circles in the west and south-west. The entire area is covered with dense tropical forests.
Namsang-Dirak River Valley: This valley covers an area of approximately 640 sq. kms. It largely expands over Khonsa and Namsang circles of Tirap and parts of Changlang District. It is covered by Burhi-Dirang River and Assam in the North, Lazu circle in the south and Khonsa circle towards the east and the west.
Tissa River-valley: This valley of the Tirap district forms a part of Patkai ranges. It covers an area of around 1214 sq. kms. The region spreads over Kanubari, Longding, Pongchao and Wakka circles and parts of Khonsa circle. It is bounded by Assam in the north, Myanmar in the south, Nagaland in the west and by Lazu, Deomali and Lower Shivalik Hills group classification. The entire area is covered with thick tropical forests.
The climate of Tirap district is hugely influenced by the topography that is marked with high hills, deep gorges and valleys through which the streams and rivers flow. In general, the elevation of land varies from around 200 feet above sea-level in the north-west to around 5000 feet over the mountains. The climate of this district varies considerably from one place to another due to its mountainous nature. Usually, the climate of Tirap district is cold and extremely moist in the lower elevations and in the valleys. The cold season prevails from the later part of the month November to February and is followed by common thunderstorms in the pre-monsoon season from the month of March to May. Very heavy and frequent monsoon showers continue from the month of May to around mid of October. Thus, it is evident from the geographical facts of Tirap district that this area is rich with valleys and has a pleasant weather that adds charm to its natural beauty.