We certainly have had more than average rain this year. Cold water and warm sun gets more of them out of the water. Summer here, therefore reduces the number out in the sun. With all the rain this year we should have a colder and earlier winter. Crocs are very wary with excellent senses. Once they realise you are on to them and they disappear so the more of them you have out of the water the more chances you will have. 
I had numerous successful bow hunts on croc in the Kafue River in Zambia. Although there are large numbers of crocs, the width of the river makes it difficult to get close to them. The Palala river is much narrower and should give you better chances to sneak up to them.
Good luck and enjoy the hunt.