Hi Mehul, Weather is superb during March-April and you can even go for paragliding. Due to rains, paragliding is not operational from June-September but still you can visit Bir. It is a wonderful village in Himachal and highly influenced by Buddhist culture. Do visit market area for some amazing cafes and Sherabling Gompa. Happy travelling!
Oh yes Bir Billing is one of the best Para Gliding site in the world. In 2015 World Cup of para gliding was held in Bir, Billing. And April to June is good season to visit there. Also trail for one of the best treks start from there do try them! Bir, Billing also has Zostel it's good place to stay at.