The average temperature varies between minimum 10 degrees in winter and maximum 32 degrees in summer. It receives an annual rainfall of approx 2500 – 3500 mm. The relative humidity varies between 50.5% in winter to 82.5% in summer.
Flora and Fauna:
Around the sanctuary various types of trees are grown in dense population. Lush greenery provides a picturesque look to the area and the population of various trees includes Ipomoea reptans, Pistia stratiotes, Ottelia Lemna minor, Potamogeton crispus, Vallisneria spiralis, Hydrilla verticillata, Eichhornia crassipes, Spirodela polyrhiza, Eleocharis plantaginea, Nymphaea alba, Nymphaea rubra Sagittaria sagittifolia, alismoides, and Azolla pinnata.
In this lake more than 215 bird species are naturally habited and the Bil is reported to support threatened species of birds like spot billed pelican, lesser adjutant stork, greater adjutant stork, black necked stork, and large whistling teal. It supports 50 fish species belonging to 19 families.
Although the Bil is famous for birds, it also contains a large variety of aquatic species. Since the Rani and Garbhanga Reserve forests are nearest to this area, herd of wild Elephants from the forests are often seen in the bil. Wild Asian Elephants, Leopards, Jungle Cats and the protected Barking Deer, Chinese Porcupine and Sambar are found in the bil.