You can check out places like Kandy, nuwera eliya (most chilled place in Srilanka ), pinnawala the elephant orphanage and the tea estates. they also have forts but you need to check for the transportation in advance.
Hi Rahul, August is the time of the southwest monsoon which brings a lot of rain to the southwestern part of Sri Lanka. The temperature is between 25 to 30 Celsius. Avoid the southwest parts of Sri Lanka during August. You can still visit Colombo, Kandy, Ella, Nuwara Eliya and Polonnaruwa.