Chitwan national park is the first and best national park in Nepal. You can visit any season and can enjoy your holiday with wild animal and natural atmosphere. In different season, you can enjoy different weather with natural beauty. Many tourists like to walk in the chitwan national park, so I would suggest them to visit February to May. At that time the old grasses will burn and new grasses will come and it will be more open and chances to see more animal from far distance. You also can do jungle walk for several days and whole day jeep safari too. If you come to chitwan in summer time, you can see animals wallowing in river, lakes or water hole. You can see them easily and not disturbing them. If you would like enjoy the Nepali festival and wildlife safari at the same time than I would suggest you to visit October and November. That time we will biggest festival like Dashain and Tihar (the festival of light).