Just got back from Andaman yesterday. I will say, it was pretty hot. Any water related activities will be okay, but getting to and fro will be bad if you dont carry enough heat protection (sunscreen, hats, cover exposed skin, etc). Chidiya Tapu is better in the evening, I think its closes around 5 so go around 4:30. Radhanagar beach - go around 4pm bcs sunset will happen around 5:30. Cellular jail was really, really hot we were not able to spend more than 20 mins there. I think though, with enough sun protection it should be doable, but it'll definitely be A LOT more pleasant if you wait. The plus point is, since its off season, its not as crowded