Is this snake poisonous, found wrapped around a tree in middle of hot summer of 40 degrees celcius, in himachal, Northern INDIA, Himalayan foothills?
This appears to be a bronzeback tree snake, which is a common species of tree snake in India. It is a slender snake with characteristic bronze body and a pale stripe down the sides. It usually has a white spot on top of its head, which I think you can see in the second picture. It should also have blue inter-scale areas if you pull the scales apart.
It is non-venomous, but like all snakes may bite if attacked.