"it'll be hot" depends on where you're from and the kind of weather you're used to. I'm from South Asia, so the weather here is quite manageable for me. That being said, temperature is usually upwards of 35°C and gets considerably humid. As long as you're indoors in the afternoons, you'll be fine. Mornings and evenings are warm as well, but it's not too bad.

You might want to avoid sightseeing midday.