also no need for socks. i.e., you can wear flip-flops (like most of the natives), just be aware that you won't be able to wear them in the temple. I'd probably advise against jeans/ t-shirt... seems a tad disrepectful. But I dress up if I am going to be in a church/ temple in this country, so i may be in the minority here.
i agree with the previous poster that you can remain cool by wearing a (below the knees) skirt or loose pants. short sleeves should be fine. sleeveless shirts probably would not be.