As the climate of Cambodia is quite hot similar to India, it's better to visit Angkor Wat in the winter season i.e. Nov - December. roughly there are 72 beautiful temples in the Angkor Wat campus spread over 600 + acres. one of the best place must visit. There are frequent domestic flights from Phnom Penh (capital) to Siem reap (Angkor Wat).
I had visited Cambodia in the month of March.. it has almost similar weather conditions like central and south India. Month of Sept/Oct can be lottle rainy.. so you can try after October or November..also check the travel restrictions.